Category Archives: Psychology

Sleep’s Positive Impact on Traumatic Memories

2376461761_b9d5047099_z

Sleep is inescapable. Some will see it as a necessary evil and others will claw at it with limited success. It may leave us (largely) immobile but it is anything but a passive state. Sleep paves the way for new neural connections to be made, clears the brain of harmful waste products, is protective against mental and physical illness, and is preferable to leaving the bed on a cold Monday morning. There is still plenty of debate as to the true function of sleep, but one key area which it appears to be important for is memory.

Broadly speaking, it is argued that sleep enhances the consolidation of recently learned information compared to wakefulness. For example, a nap as short as 5-10 minutes has been shown to enhance memory and improve problem solving compared to wakefulness following learning. Moreover, rapid eye movement sleep has been linked to enhanced memory for emotional information, and to reducing the emotional strength of such memories. This suggests that different aspects of sleep are important for different types of memories and highlights some potential ways we can modify the impact of negative ones. What if we could interfere with the brain’s ability to form negative memories? More specifically, what if we could interfere with traumatic and intrusive memories which form the basis of illnesses such as post-traumatic stress disorder (PTSD)? Recent research seems to suggest this may be possible.

PTSD is a psychiatric disorder characterised by flashbacks and nightmares, avoidance of the situation in which the trauma occurred, and emotional numbing. It is the result of a traumatic event which can be wide in scope (e.g. warfare, sexual abuse, hospital admission) and individuals with PTSD will often find themselves transported back to the event. These ‘memories’ are intrusive in nature and, understandably, highly distressing. It has been suggested that interfering with the consolidation of intrusive memories at the time they are formed (or shortly afterwards) may help those who are likely to go on to experience PTSD. Evidence to support this would unlock a powerful early intervention tool for those likely to experience trauma (e.g. refugees or soldiers). One way this can be achieved, as you have likely guessed, is through manipulating sleep.

In 2015, a study conducted at the University of Oxford explored whether sleep deprivation might be protective against intrusive traumatic memories. Participants were brought into the laboratory and randomised to either a sleep deprivation or sleep group. They were then shown a film containing traumatic scenes which lasted just over 15 minutes. Following the film, participants were either kept awake or allowed to sleep. On the following day, participants completed a questionnaire measure of PTSD symptomology and were then asked to complete a diary to track the intrusiveness, content, distress, and presence of mental imagery associated with the traumatic film for 6 days.

The Oxford group, led by Dr. Kate Porcheret, found that a night of sleep deprivation, compared to sleep as normal, reduced the intrusiveness of experimental-trauma memories. The sleep deprivation group reported fewer intrusive memories, lower PTSD symptoms scores, and (non-significantly) reduced distress of the intrusive memories. However, this effect was only found for the first two days and sleep deprivation was found to confer no protection against intrusive memories after 6 days. This suggests that sleep deprivation immediately after the traumatic experience can reduce its intrusiveness but only in the short term. Sorted. Sleep deprivation, paradoxically, confers some protective against traumatic memories. Right? Well, to quote Ben Goldacre, “I think you’ll find it’s a bit more complicated than that”.

A study published last December in the aptly named journal SLEEP has injected additional complexity to this issue. Dr. Birgit Kleim and colleagues assessed the impact of a single night of sleep deprivation on distress and intrusiveness of traumatic memories for seven, rather than six, days. They asked 65 female participants to watch two 12 minute films of a neutral (nature documentary) or traumatic (horror film) nature in a randomised order. Participants were either allowed to sleep at home or kept awake. They were then asked to keep an intrusion diary which required participants to note when they experienced intrusive memories related to the film and rate their vividness, intrusiveness, content, and distress each day. The participants were then followed-up a week later.

So, what did they find? For the first two days following the films, there was no significant difference between the sleep or wake groups on distress or intrusiveness of the traumatic film. However, by days 6 and 7 there was a significant reduction in distress and intrusiveness for the sleep compared to wake group. By contrast, there were no difference in intrusiveness or distress of the neutral film for the sleep and wake groups. The effects found were specific for the traumatic, emotional, memory.

This second study showed that sleep deprivation does not provide a protective effect against intrusive emotional memories. Instead, they argued that sleep immediately following the trauma experience has long-term benefits on reducing the distress and intrusions associated with the traumatic memory. Nonetheless, this study does not directly contradict the one conducted by Porcheret and colleagues at Oxford. Although non-significant, distress was higher for the sleep compared to sleep deprivation group which suggests that sleep deprivation may serve an immediate protective role against traumatic memories. However, this effect seems to reverse in the relative long-term.

Why should this be so? Well, we know that memories – particularly emotional ones – are strengthened by a period of sleep. This would suggest that sleep following a traumatic experience would strengthen the memory for that experience and thus enhance the intrusiveness of a traumatic memory. This could explain why sleep deprivation produced a reduction in intrusiveness and distress for the Oxford study as the lack of sleep interfered with the ability to lay down the negative memory. However, the explanation for these studies is less clear. The authors argue that sleep deprivation is protective against intrusive memories in the short term but not the long-term. Kleim and colleagues claim that sleep following the traumatic experience may initially make it more distressing but also encourage appropriate integration of the memory alongside existing memories. This, they argue, reduces the chance that the traumatic memory will be intrusive and uncontrollable – a cardinal symptom of PTSD.

We already know that rapid eye movement sleep (REM) is associated with a reduction in the intensity of emotional images (van der Helm et al., 2011). Kleim’s study found that increased REM was associated with more, not less, intrusions. Instead, they argue that other stages of sleep are responsible for the reduction in distress and intrusions seen perhaps through a different mechanism. However, this does not state that the memory should be remembered more poorly (i.e. deliberate recall of the film would be unaffected). Rather it seems that deliberate memory recall and intrusive memories may be guided by different mechanisms and differentially affected by sleep. Neither the Porcheret or Kleim study asked participants to take a memory test of their explicit recall of the films. However, the diary studies suggest that all participants were accurate in recalling the films throughout the study period and deliberate recall does not appear to be associated with intrusive memory frequency.

tetris

A similar distinction between intrusive and deliberate recall of memories was found by another study attempting to reduce the negative impact of traumatic memories. Indeed, these are the not the first studies which have attempted to interfere with the consolidation of traumatic memories. A more colourful way of achieving this has been shown through getting people to play Tetris. For the uninitiated, Tetris is a simple game whereby you match coloured bricks of different shapes into lines of 4. They fall from the top of the screen and you have to rotate the shapes to make them line-up and disappear. In 2009, Dr Emily Holmes and colleagues at the University of Oxford showed that if they got participants to play Tetris for 10 minutes, half an hour after a traumatic film, they saw a reduction in subsequent intrusions or “flashbacks”. This effect was found for over a week follow-up during which an intrusion diary was kept. Interestingly, deliberate recall of the film was not impaired when tested at one-week follow-up. This also suggests it is possible to reduce the intrusive nature of a traumatic memory without reducing the memory for the event.

Of course, it is difficult to get someone in a warzone to take out their Tetris ration or take a nap following a fire-fight, but it highlights that it is possible to reduce the negative impact of traumatic memories. These pieces of research suggest that manipulating sleep is a viable way to reduce the ‘flashback’ quality of traumatic memories. Although promoting sleep for those having recently experienced a traumatic episode might raise its own difficulties, it heralds a step towards early intervention for PTSD. If nothing else, they remind us that sleep is important for the consolidation of memory alongside existing memory networks and how little we know about the effect of sleep on memory.

One thing we do know for sure: sleep is anything but a passive and simple state.

Inquisitive Tortoise

References:

Holmes, E. A., James, E. L., Coode-Bate, T., & Deeprose, C. (2009). Can playing the computer game “Tetris” reduce the build-up of flashbacks for trauma? A proposal from cognitive science. PloS one, 4(1), e4153.

Kleim, B., Wysokowsky, J., Schmid, N., Seifritz, E., & Rasch, B. (2016). Effects of Sleep After Experimental Trauma on Intrusive Emotional Memories. Sleep.

Porcheret, K., Holmes, E. A., Goodwin, G. M., Foster, R. G., & Wulff, K. (2015). Psychological effect of an analogue traumatic event reduced by sleep deprivation. SLEEP, 38(7).

van der Helm, E., Yao, J., Dutt, S., Rao, V., Saletin, J. M., & Walker, M. P. (2011). REM sleep depotentiates amygdala activity to previous emotional experiences. Current Biology, 21(23), 2029-2032.

Image Credits:

Bad Memory (Header)

Leave a comment

Filed under Dreaming, Memory, Psychology, Sleep Science, Trauma

What Have Fairy Tales Got to Do With Sleep Medicine?

Sleeping Beauty.jpg

“Fairy tales? That’s the best you could think of to drag people in?”

“What’s wrong with it? It’s accurate…”

“I dunno man, you used to be all about the science. Now this feels all click-bait territory *shudders*”

“…”

By fairy tales, I am of course referring to sleeping beauty. Not a champion of feminist thought, this story tells the tale of a young woman who awaits the kiss of a prince to awaken her from an eternal slumber. Although there is no disorder which makes you sleep indefinitely there is a close contender with something called Kleine-Levin syndrome (KLS) – also known as ‘sleeping beauty’ syndrome.

What is Kleine-Levin syndrome?

Kleine-Levin syndrome is an episodic and extremely rare sleep disorder whereby the individual goes through periods of excessive sleepiness (hypersomnia). We all go through periods of feeling exhausted and may find ourselves sleeping for that bit longer. Maybe in extreme cases we’ve found that we’ve spent the whole day in bed fast asleep (thanks new year’s). However, imagine spending up to 20 hours a day asleep for weeks, or even months with no indication when you’ll ‘wake up’ and go back to normal. You miss school, friends, hobbies, and significant portions of your life as your teenage years drifts steadily away. Your dreams seem more real than reality and you lose interest in everything around you. This is a taste of what those with KLS experience and have to deal with.

Other than spending most of the day asleep, sufferers also experience memory, speech, and comprehension problems. In addition, hallucinations, derealisation (feeling as if in a dream), hypersexuality and megaphagia (increased eating behaviour) and paranoia also co-occur with the sleep and cognitive symptoms. It usually tends to emerge around adolescence and usually runs its course over about 8 years (with individual variability). Unsurprisingly, KLS causes significant disruption to academic performance, social lives, and sometimes memory of affected individuals.

What is its prevalence?

It is such a rare disorder that it has been difficult to get an accurate representation of its prevalence. We do know is that it is more prevalent in males but it seems to persist for longer in females for yet unknown reason. Some studies claim the prevalence is as low as 1 in a million but there is little research to support this number. Due to its rarity, most of our available knowledge on this study has been gained through case studies.

What causes this disorder?

This is uncertain although there is research attempting to shed light on this enigmatic illness. A systematic review carried out just over a decade ago found that in over 40% of reported cases, the first episode of KL-syndrome was preceded by an infection or fever. However, in 39% of cases there was no obvious precipitating trigger and the same lack of trigger is found in 84% of subsequent episodes of KL-syndrome. Although onset tends to occur during the latter months of the year, there is no strong argument for why this might be the case. Moreover, the disease may appear to disappear with little understanding why the symptoms disappear.

The link between infections and KLS has led some to argue that it may have an immune-system cause. However, there is little evidence for a link between dysfunctional immune functioning and KLS. Researchers have found some support for a link between certain types of hypersomnia and autoimmunity disorders but it is still unclear whether this extends to KLS.

A study by Dr. Jing Wang and colleagues at the Binzhou Medical University Hospital examined a large group of individuals with KLS (N=44) to identify potential markers of KLS. They found that a large subset of these individuals (N=34) were found to have reductions in a chemical called orexin in their cerebrospinal fluid (CSF) during a relapse compared to a period of remission. Orexin is a neurochemical which is important for wakefulness and is reduced in another disorder characterised by hypersomnia – narcolepsy. However, levels of orexin were not as low as those seen in narcolepsy. Interestingly, this cohort also showed a similar pattern of viral infection preceding the initial episode of hypersomnia / KLS.

Treatment

Again, it should come with little surprise that there are limited treatment options for those with KLS. One route is to reduce the fatigue through stimulants. However, this approach is not effective for other symptoms of the disorder. A different approach is to treat KLS using a mood stabiliser, lithium, which has shown some promise in reducing the length and frequency of episodes, and in reducing the behavioural symptoms. However, evidence for the efficacy of this treatment is limited and it forms one of many possible pharmacological treatments which require wider study.

Difficulties in Diagnosis

This is an extremely rare disorder and not many will have had experience with this diagnosis. However, it is treated with scepticism from some physicians and the general public. Some see it as laziness or not unusual for adolescents and students to sleep for most of the day. It is also not unusual for an individual with KLS to be given a diagnosis of depression in light of similar symptoms to an unknowing physician. A diagnosis of KLS can be laborious to reach as it will be given after identifying whether the individual’s symptoms are not better explained by a whole host of other diagnoses or causes. We have known about this disorder for more than a century and yet we have no convincing theory for why it occurs or how to treat it.

Although there is a lot we don’t know about KLS there is still active research determined to better understand and treat this disorder. If you’re interested in learning more about what it’s like to live with this illness this documentary is a good start.

Inquisitive Tortoise

References:

Arnulf, I., Zeitzer, J. M., File, J., Farber, N., & Mignot, E. (2005). Kleine–Levin syndrome: a systematic review of 186 cases in the literature. Brain,128(12), 2763-2776.

Barateau, L., Lopez, R., Arnulf, I., Lecendreux, M., Franco, P., Drouot, X., … & Dauvilliers, Y. (2017). Comorbidity between central disorders of hypersomnolence and immune-based disorders. Neurology, 88(1), 93-100.

Kornum, B. R., Rico, T., Lin, L., Huang, Y. S., Arnulf, I., Jennum, P., & Mignot, E. (2015). Serum cytokine levels in Kleine–Levin syndrome. Sleep medicine, 16(8), 961-965.

Leu-Semenescu, S., Le Corvec, T., Groos, E., Lavault, S., Golmard, J. L., & Arnulf, I. (2015). Lithium therapy in Kleine-Levin syndrome An open-label, controlled study in 130 patients. Neurology, 85(19), 1655-1662.

Poppe, M., Friebel, D., Reuner, U., Todt, H., Koch, R., & Heubner, G. (2003). The Kleine-Levin Syndrome. Neuropediatrics, 34(03), 113-119.

Wang, J. Y., Han, F., Dong, S. X., Li, J., An, P., Zhang, X. Z., … & Yan, H. (2016). Cerebrospinal Fluid Orexin A Levels and Autonomic Function in Kleine-Levin Syndrome. Sleep, 39(4), 855.

Image Credits:

Sleeping Beauty (Header)

Leave a comment

Filed under Media, Psychology, Sleep Science, Work and Society

Why Do We Dream?

dreaming1

Key Dream Research Equipment

“What does my dream mean?!”

“Sorry…?”

“I’ve heard you study sleep. I mean I think I’ve worked it out myself but I wanted an expert opinion.”

“Erm…”

It doesn’t take long to drift into questions about dream analysis when I tell people that I study sleep. I don’t entirely blame them. It’s a subject which has fascinated society for millennia and it doesn’t look like that is going to stop any time soon. I’m sure most of us have had a dream which we are convinced has some greater significance: a dream about facing our fears or that person who you hadn’t thought about for years.

In the distant past, dreams were associated with divine will and prophetic qualities. Ancient Egyptian and Greek scholars produced dream manuals which were used to interpret nightly visions. Flash forward to the 19th and early 20th century and there was a shift towards understanding dreams in terms of their psychological causes and consequences. It was not until 1953 with the discovery of rapid eye movement (REM) sleep that the objective study of dreaming was possible.

Since then, we have come to appreciate that not all dreams are not created equal. Depending on which stage of sleep the dream is recalled from will depend on the type of dream. Firstly, dreaming does not only occur during rapid eye movement (REM) sleep but can occur at any stage during the sleep cycle. Dreams at sleep onset and during short naps appear to be relatively faithful, if not stripped back, representations of daily activities. By contrast, dreams reported during REM sleep and after longer periods of sleep appear more bizarre and less clearly linked to daytime activities.

So why do we dream? What attempts have there been to try to understand these nightly visions of the surreal?

Wish Fulfilment

Freud stated in ‘The Interpretation of Dreams’ that all dreams were wish fulfilment of our uninhibited desire. The dream provided an outlet for these desires and prevented them seeping into wakefulness. The dream (manifest) content could thus be interpreted and inform the analyst about the unconscious desires of an individual. The latent, or unremembered and unconscious, dream content could be reached through employing dream analysis and psychoanalytic techniques. Although you can still buy manuals which claim to teach you how to analyse dreams in line with early psychoanalytical thought, the validity of these are questionable at best. The steps required to reach the ‘latent content’ can be idiomatic and despite claims that an airplane can represent unconscious desires sometimes “…a cigar is just a cigar”.

Dreaming to Remember

It has been shown that dreaming is linked to the activities which we complete during the day. This should come with little surprise to most. We can often pinpoint our dreams back to activities we have completed during the day – even if they appear in bizarre contexts.

Robert Stickgold at the Department of Psychiatry, University of Harvard, showed this with a simple experiment. Participants were required to play Tetris at fixed periods and to sleep in a monitored laboratory setting. During this time, participants were asked about their thoughts and dreams in the first hour of attempted sleep.  He found that by asking participants to play Tetris for extended period of time that a significant number of sleep-onset dreams and images were found to be linked to Tetris (i.e. images of the blocks falling into place and lines of blocks disappearing when complete).

tetris

A study from the same group led by Erin Wamsley at the University of Harvard built on this by exploring whether the presence of task-relevant dreams was associated with performance. They asked participants to complete a virtual navigation task whereby they had to reach a goal (e.g. a tree). Participants were then re-tested just over 4 hours after the initial completion of this task.

Half of the group were then provided with an opportunity to nap and the other half remained awake. Unsurprisingly, from what we already know, the nap group were found to show a greater improvement on the task at re-test. Interestingly, and importantly for dreaming, the participants who dreamed about the maze during the nap also reported the greatest re-test improvement. Okay, perhaps this might simply have been due to the fact that these participants were simply thinking of the task more? However, this doesn’t appear to be the case. The wake participants were also asked about their task-relevant thoughts but the researchers found no benefit to re-test performance here.

Collectively, these studies suggest that dreaming may be a result of the brain consolidating and organising new memories alongside existing ones. However, they don’t tell us that dreaming is responsible for our improvement but that dreaming may be a marker of it.

Activation Synthesis Theory (and Dreaming to Forget)

Other theories suggest that dreaming has little relevance to memory or other functions. The Activation Synthesis theory proposed by Allan Hobson and Robert McCarley in 1977 claims that dreaming is the product of seemingly random or automatic brain activity produced during REM sleep.

These ‘random’ activations have their origin in the brain stem and are transmitted to the forebrain during REM sleep. The cortex then compares this activation against previous memories to make sense of the neural activity produced by the brain stem. It is claimed that a similar mechanism may explain non-sleep hallucinations and dreaming. This theory forms the basis for another hypothesis for why we dream: not to remember but to forget. This should seem counter-intuitive based on what we know about sleep and memory – and all that advice you’re given by teachers or colleagues before an important exam or meeting.

However, Francis Crick (yes, that Francis Crick) and Graeme Mitchison argued in 1983 that sleep has an important role in identifying faulty connections within the brain – an inevitable problem facing a neural network of sufficient complexity. These ‘faults’ arise during development and as a part of the multitudinous memories and connections we develop throughout any ordinary day. During REM sleep, these ‘faults’ are dampened down and their connections weakened. This ensures the brain works efficiently.

So, where does dreaming fit in?

Quite simply the ‘faults’ in the brain are experienced as dreams. Our dreams are the connections which our brains’ are trying to suppress during REM sleep. The overall purpose of such a mechanism is to ensure the efficient functioning of a brain with finite processing power.

However, if our dreams are the memories we are trying to erase, in one form or another, why do we have recurrent dreams? Crick claims that this is tricky for the theory but may be as a result of the threatening nature of recurrent dreams. The anxiety and fear associated with such dreams is likely to wake up the dreamer and to subsequently be remembered. This may interfere with the reverse learning process.

Primitive instinct rehearsal theory of dreaming

Another appealing theory is that dreaming is not a product of vital or random brain activity but rather that it serves an evolutionary advantage. More specifically, it has been claimed that dreams may help us deal with threatening situations in our daily lives by giving us an opportunity to practise overcoming them. In turn this increases our survival odds and also increases the chance we will successfully reproduce – passing on that ability to dream to our offspring.

Anecdotally this might explain why anxiety and fearful dreams are commonly reported by many different people, and why they share a common theme. However, like Freud, this theory assumes that dream content must have a distinct purpose. It’s hard to falsify such a theory and provide evidence which would conclusively disprove its existence as many dreams could conceivably be interpreted in a practise or threat-related manner.

Dreaming and Creativity

Finally, it’s an old claim that creativity and dreaming are linked together. Authors such as Mary Shelley and Steven King relate their tales of horror back to dreams they’ve remembered. Salvador Dali enjoyed the phantasmagorical images produced through his dreams and used them as inspiration for his surrealist art.

What does the science say about creativity and dreaming?

dreaming2

Surveys of students’ ability to remember and recall dreams correlates with openness to new experiences, fantasy proneness, and may even be associated with a lesser ability to filter out environmental input. Cumulatively, this suggests that traits associated with creativity and ‘thinking outside the box’ are associated with an ability to recall dreams. However, this does not mean that we dream in order to improve creativity but that creativity is likely a product of bizarre, frightening and fantastical dreams. We benefit from dreaming but only insomuch as an incidental source of inspiration.

Overall, even though the content of your dreams may not necessarily provide a convenient road to your hidden thoughts and desires, they can provide us some fascinating insights into the sleeping brain. Despite frustrated responses from others, that remains my response when they ask about last night’s dream about planes, trains and giant chickens.

Don’t ask.

Inquisitive Tortoise

References:

Crick, F., & Mitchison, G. (1983). The function of dream sleep. Nature, 304(5922), 111-114.

Stickgold, R., Malia, A., Maguire, D., Roddenberry, D., & O’Connor, M. (2000). Replaying the game: hypnagogic images in normals and amnesics. Science, 290(5490), 350-353.

Wamsley, E. J., & Stickgold, R. (2010). Dreaming and offline memory processing. Current Biology, 20(23), R1010-R1013.

Wamsley, E. J., Perry, K., Djonlagic, I., Reaven, L. B., & Stickgold, R. (2010). Cognitive replay of visuomotor learning at sleep onset: temporal dynamics and relationship to task performance. Sleep, 33(1), 59-68.

Image Credits:

Dream Catcher (Header)

Tetris (Body Text)

Nightmare (Body Text)

 

Leave a comment

Filed under Dreaming, Literature, Psychology, Sleep Science

Juggling sleep with work: what are the long-term effects?

092016_FunwithInsomnia.png

It’s 6am again. The unrelenting tone from your bedside table reminds you it’s time to roll out of your duvet cocoon and get ready to face the working world. You swat your shrieking phone as it gets louder and more persistent. A quick swipe of the screen and you notice the day. It’s Friday.

A relieved smile spreads across your face.

Well, at least tomorrow means a lie-in.

The typical working week for most will involve dragging ourselves out of our warm, cosy beds and forcing our legs to make the long cold trek to the bathroom. Yet, we know that come the weekend we will be able to catch up, even briefly, on the sleep denied to us during the week. Although we will moan to friends and colleagues, our society seems perfectly content with depriving ourselves of sleep during the working week only to catch it up during the weekend. We would likely prefer a few minutes (or hours) more in the morning, but many of us don’t consider this practice as detrimental to our health. The shift from short to long sleep is considered a part of life.

This is far from sensible as the effects of sleep deprivation are well known, even if you don’t spend your days buried in journals with helpful names such as ‘Sleep’.

There is a name (there always is) for the shifting of sleep patterns throughout the working week – social jet lag. This refers to the changes in our sleep timing and duration depending on when we’re working (e.g. sleeping less on workdays and more on free days), and how this can confuse our internal clocks which try to keep our sleep patterns regular and predictable. These are the same internal clocks which influence whether you are an owl or a lark – an evening or morning person. This misalignment affects people differently, and it is not hard to see why night owls, who want to sleep later and wake up later, may suffer more.

Social jet lag is a problem for society. It is associated with depression, an increased risk for heart disease, more frequent smoking, and increased stimulant use in general. Understandably, the effects seen from sleep deprivation, including difficulties in concentration, memory, social functioning and mood, are also associated with social jet lag.

Despite the mental and physical health issues reported, the available data had been largely correlational. This makes it hard to draw definite conclusions on whether society’s current schedule of sleep is bad for us in the long-term.

However, a recent study published earlier this year has attempted to address this.  A team of researchers at the University of Harvard sought to understand whether repetitive patterns of sleep restriction and catch-up sleep have a negative impact on our health and wellbeing, or whether we may simply get used to it.

More specifically, they wanted to try to work out whether there is a difference in our own subjective view of this sleep pattern and how our body, behind the scenes, might respond in terms of stress and immune functioning. Do we adapt to the sleep loss in both domains? Previous evidence suggested we might not but this hadn’t been convincingly tested over a long period until now.

To assess these questions, they recruited 14 participants who were studied in a controlled hospital setting over three weeks. During each week, the participants spent 5 days sleeping for 4 hours and 2 days sleeping for 8 hours. After a few months, the same participants were invited back to conduct the same experiment sleeping for 8 hours each day over the 25-day experiment. The results of each were compared to try to understand the impact of the working week’s sleep patterns.

The group asked participants about how sleepy they felt, their perceived effort to do anything, and how stressed they felt each day at 4 hour intervals throughout the study. Alongside this, objective measures of stress and immune functioning were also assessed via blood samples collected on 7 of the 25 study days. Specifically, they looked at the levels of a chemical messenger of the immune system known to promote inflammation, interleukin-6, and the levels (total and stability) of cortisol, a hormone released in response to stress (amongst other factors).

The participants’ diet and exercise were controlled to reduce the impact of these variables, and they could have visitors to reduce the impact of isolation, and deviation from normal routines, where possible.

So, what did they find?

Over the three weeks, when participants were restricted to only 4 hours’ sleep they (unsurprisingly) felt sleepier and reported a greater effort to do anything compared to when than when they could sleep for 8 hours (e.g. during the weekend in the restricted condition and every day for the control condition). Interestingly, the ‘effort to do anything’ ratings became increasingly similar for the restricted and control condition over the three weeks, and participants reported no extra stress when asked to halve their sleep to 4 hours for the restriction condition. Overall, this suggests that participants, although sleepy, were subjectively fine with the simulated typical work sleep pattern. There was even evidence that participants started to adapt as their reported effort to carry out tasks diminished by the third week of only 4 hours sleep.

By contrast, the objective results showed a less optimistic picture. The researchers found an increased dysregulation of cortisol as the weeks of sleep restriction went on, and an increase in morning cortisol compared to the control condition. However, both returned to normal following recovery sleep at the weekends. In terms of immune system functioning, unstimulated IL-6 levels were significantly higher for the first week of sleep restriction and then remained elevated but non-significantly so compared to the control condition. For the stimulated IL-6 levels, these were significantly elevated during the week for the second and third week of the restriction condition compared to the control.

These results highlight that although participants seemed to be no more stressed subjectively in depriving themselves of sleep during the week, it seems that this pattern of sleep was not something the body simply ‘gets used to’. Instead it seems that the body still shows an increase in the inflammatory marker IL-6, increased cortisol upon awakening, increased dysregulation of cortisol, and inhibition of IL-6 in the presence of cortisol-like molecule. This hints at a heightened stress and immune response which, importantly, does not appear to adapt to the effects of chronic sleep loss during the week. Although recovery sleep during the weekend mitigated this effect somewhat, there was some evidence to suggest that two days was not enough to return immune functioning (stimulated IL-6) back to normal.

You may be thinking that increases in IL-6 and increased inhibition of IL-6 seem counter-intuitive, but the authors had a potential explanation. They highlighted that this may be the product of a particularly active immune response following chronic sleep to deal with its physiological effects (i.e. the increased sensitivity to cortisol’s effect is lessened due to a need to remove toxins built up in the brain).

In addition, you may also want to argue that 4 hours sleep during the week is hardly typical of most people’s work schedule, and that this experiment is far from representative of real life. However, this is a weak argument as the effects of sleep deprivation have already shown to be cumulative. It is more likely that losing an hour or two during the workday has negative effects but over longer periods than are suggested by this study.

So, it seems that even though we may consider depriving ourselves of sleep during the week manageable, and even get used to it, the same cannot be said for our body. This study suggests that we don’t get used to sleep loss during the working week. Moreover, recovery sleep during the weekends may not be enough to compensate for a week of fighting our internal clocks.

Although this study only examined a small number of people and a small number of specific measures, it still highlights the persistent effects of restricted sleep on our immune and stress systems. It also provides some hints as to how we may be able to successfully convince ourselves that this pattern of sleep is not detrimental to our health. If we feel subjectively okay, if not slightly lethargic, about this lifestyle then there would be no immediate drive to change it – at an individual or society level.

Granted, necessity and an inability to pay the bills may also be powering this too…

Inquisitive Tortoise

References:

Rutters, F., Lemmens, S. G., Adam, T. C., Bremmer, M. A., Elders, P. J., Nijpels, G., & Dekker, J. M. (2014). Is social jetlag associated with an adverse endocrine, behavioral, and cardiovascular risk profile?. Journal of biological rhythms, 0748730414550199.

Simpson, N. S., Diolombi, M., Scott-Sutherland, J., Yang, H., Bhatt, V., Gautam, S., … & Haack, M. (2016). Repeating patterns of sleep restriction and recovery: Do we get used to it?. Brain, Behavior, and Immunity.

Van Dongen, H. P., Maislin, G., Mullington, J. M., & Dinges, D. F. (2003). The cumulative cost of additional wakefulness: dose-response effects on neurobehavioral functions and sleep physiology from chronic sleep restriction and total sleep deprivation. SLEEP-NEW YORK THEN WESTCHESTER-, 26(2), 117-129.

van Leeuwen, W. M., Lehto, M., Karisola, P., Lindholm, H., Luukkonen, R., Sallinen, M., … & Alenius, H. (2009). Sleep restriction increases the risk of developing cardiovascular diseases by augmenting proinflammatory responses through IL-17 and CRP. PloS one, 4(2).

Extra Reading:

http://www.huffingtonpost.com/margaux-mcgrath/social-jet-lag-and-sleep_b_7842074.html

Image Credits:

Header Image

Leave a comment

Filed under PhD, Psychology, Sleep Science, Uncategorized, Work and Society

Can a Lack of Sleep Kill You?

4929686837_6ac689b7c1_z

“Have you forgotten so easily?” the subject asked. “We are you. We are the madness that lurks within you all, begging to be free at every moment in your deepest animal mind. We are what you hide from in your beds every night. We are what you sedate into silence and paralysis when you go to the nocturnal haven where we cannot tread.”

Surviving participant from ‘The Russian Sleep Experiment’ in the late 1940s. This volunteer went 15 days without sleep.

Before you start looking over your shoulder for the demonic presence presented above, don’t be alarmed. The quote above is from a piece of horror fiction from a website called Creepy Pasta and is completely fake. I hope.

I wanted to start with this as Halloween is fast approaching and I thought that a more fiendish sleep myth was worth looking at. Can a lack of sleep be directly responsible for your death?

A complete lack of sleep is something new parents and those of us with upcoming deadlines may know all too well. It’s draining, depressing, and leaves us eyeing up any available floor space as prime real-estate for your exhausted brain and body.

We have already looked at the effects of getting too little or too much sleep in my earlier post, but not the more extreme side of this. Research conducted with animals at the end of the 19th and the start of the 20th century suggests that not only is sleep important, but that it is vital for sustaining life. In experiments which looked at puppies, cats and rats, it was found that after anything from a few days to around a month of no to very little sleep would lead to death in these animals. This should be taken with a pinch of salt as animals tend to have to be forced to stay awake, and this is typically through stressful contraptions.

How about humans though? What is the longest any one has gone without sleep and gone on to tell the tale?

Well there are two main sources which we can look at. Firstly, there are the people who have willingly deprived themselves of sleep and secondly we can look at people who no longer sleep. Starting with those strange souls who willingly deprive themselves of shut-eye we can look towards a reality TV-show, our trusty sleep-deprived student population, and a couple of radio DJs to start to answer this question.

People are seemingly keen to show off their endurance when it comes to neglecting or overindulging in the necessities of life. Some will do it to win a fabulous prize and others because… Well I’m sure they know why they do it. Anyway, one such contest is relevant here.

The reality TV show ‘Shattered’ provided contestants a chance to win £100,000. All they had to do was be the last one standing in a competition to stay awake the longest. The show was screened on channel 4 in 2004 and its questionable premise didn’t put off a group of eager participants keen to deprive themselves of sleep for fame and glory. The winner stayed awake ultimately for 178 hours. The show capped the length of time participants could remain awake for, and a number of increasingly soporific tasks eventually weeded out one overall victor. If you are interested in this ‘experiment’ you can watch it here.

However, 178 hours was meagre compared to the next contenders. It seems that at the end of the 1950s and early 1960s there was a surge in radio DJs attempting to promote themselves and further their careers in bizarre ways. Collectively they felt that staying awake and parading their increasingly fatigued selves in a department store window was the way to do this.

Our first member of the media to tackle a lack of sleep was a young radio announcer referred to as W.A. He managed to stay awake for a total of 220 hours or just over 9 days. Previously, another radio DJ by the name of Peter Tripp had managed to last 201 hours without sleep. Finally, our last radio DJ, Tom Rounds, shortly after moving to Honolulu in 1959, managed to stay awake for 260 hours and appeared to suffer no long-term effects of his sleep deprivation.

218250971_6be4b8c53a_m.jpg

Is sleep necessary for sustaining life?

However, their collective records did not last long. The radio DJs were swiftly beaten in 1964 by the efforts of a student called Randy Gardener. Randy was a 17 years old student who felt that he could provide something more interesting than a papier-mâché volcano to present at his school’s science fair. He went without sleep for 264.4 hours, which equates to about 11 days and 24 minutes, and supposedly suffered no long-term problems. The often cited report claims that Randy suffered no ill effects of his experiment, yet others claim he experienced hallucinations, paranoia, fluctuations in mood, and problems in short term memory and concentration. The latter would fit with what we know about acute sleep disturbances (Petrovsky et al. 2014; Kahn-Greene et al., 2007).

Interesting, there have been reports of others having seemingly beaten Randy’s record and by a sizeable margin. These have not been validated in part due to scientists and those responsible for recording ‘world records’ not wanting to encourage these record attempts. For example, the Guinness Book of World Records no longer prints updates to the sleep deprivation record since Randy Gardener.

Okay, so far it looks like we can go a long time without sleep and survive. This seems to suggest that although we need sleep (try not sleeping tonight if you’re not convinced), an acute loss is not going to be directly responsible for your demise (but likely indirectly).

Let’s move to the second source of human sleep loss evidence now: those who no longer possess the ability to sleep.

We’ve already looked at people who for one reason or another have decided to willingly deprive themselves of sleep. Yet, for some the ability to sleep is lost. Although insomnia fits this bill, in this case we are referring to the rare genetic brain disease known as Fatal Familial Insomnia (FFI). As the name suggests, this disease is associated with a prolonged and severe insomnia which ultimately leads to death. There are some experimental treatments to delay the fatal consequences but these may only provide a couple of extra years at best.

Fatal familial insomnia is a prion disease. Prions are misfolded proteins that cause damage to the brain as they clump together. In the case of FFI, these prions clump at a specific part of the brain known as the thalamus. The thalamus plays a prominent role in regulating sleep and in coordinating the brain as it drifts deeper and deeper in somnolence. As a result, as the damage to the thalamus accumulates this unsurprisingly leads to worsening insomnia.

These individuals seemingly sleep very little or not at all and will survive from a few months to about several years following the presentation of symptoms. The course of this illness would suggest that it is possible to die from sleep deprivation, at least at extreme durations. However, we can’t say that it is the complete lack of sleep alone which kills those with FFI as damage to the thalamus affects other functions rather than just sleep. Moreover, as this disease is so rare that it would be wrong to make a firm conclusion based on this alone. More likely, it seems that the lack of sleep contributes significantly, but not completely, to the decline of those with this illness.

So, what’s the verdict on sleep deprivation being capable of deadly consequences?

The research in animals suggests it can be but the human studies tell another story. Although common myths and horror stories might like to toy with our inbuilt fears about the unknown, it looks like a lack of sleep will not directly lead to your death. Instead, the host of effects already covered may be the true driver between mortality and sleep loss.

Inquisitive Tortoise

References:

Luby, E. D., Frohman, C. E., Grisell, J. L., Lenzo, J. E., & Gottlieb, J. S. (1960). Sleep deprivation: effects on behavior, thinking, motor performance, and biological energy transfer systems. Psychosomatic Medicine, 22(3), 182-192.

Petrovsky, N., Ettinger, U., Hill, A., Frenzel, L., Meyhöfer, I., Wagner, M., … & Kumari, V. (2014). Sleep deprivation disrupts prepulse inhibition and induces psychosis-like symptoms in healthy humans. The Journal of Neuroscience, 34(27), 9134-9140.

** http://creepypasta.wikia.com/wiki/The_Russian_Sleep_Experiment

**In case you find yourself wanting to read the rest of the fictitious foray into the effects of sleep deprivation.

Image Credits:

Header Image

Cat Image

Leave a comment

Filed under General Interest, Literature, Media, Psychology, Sleep Science

Why Do We Sleep? The Brain’s Waste Disposal System

Brain Pic

How does sleep help this fellow’s tubular brain remain healthy?

“Okay, smart guy so why do we sleep then? Bet you can’t answer that one…”

“Well… How long have you got? There’s a fair bit of content to co- Hey! Don’t run away! It won’t take me that long, honest!”

Sleep is complex and despite the intuitive explanation for why we drift off on a daily basis, we are still in our infancy when it comes to understanding how and why this occurs. We know that for the most part a good night’s sleep is refreshing and important for paying attention at work, school, or carrying out most tasks.However, how sleep keeps us functioning is less black and white.

There is no one reason why we need to sleep. For example, it maintains us mentally and physically in a number of ways, including:

  • Memory consolidation
  • Growth
  • Mental health
  • Brain maintenance

We could spend a lot of time covering all of these in considerable detail, but for now we’ll look at brain maintenance. Brain maintenance may seem like a broad category but it fits into our recent developments in understanding how the brain deals with waste materials.

The Brain’s Waste Disposal System

All cells in the body produce waste products of some description. This may be as a result of metabolic functioning, protein synthesis, and cell death, and these are filtered out via the lymphatic system.

The brain, unsurprisingly, is no different. However, until recently it was not clear how the brain solved this waste management problem. That was until the recent discovery of the glymphatic system.

Glymphatic System: The Brain’s Clearance System?

So what is the glymphatic system, and why should we care? Well firstly, its discovery has been hailed as important step in understanding major neuropathologies such as Alzheimer’s disease. Although, there’s a while to go before we should get too excited about this.

As mentioned above, the cells within your body work and produce potentially toxic waste products. The body has an effective way of getting rid of these through multitudinous lymphatic vessels. Yet, until recently it wasn’t known how the central nervous system, that is the spinal cord and the brain, manage to remove their waste products.

In a similar way to the lymphatic system, it has been proposed than the glymphatic system works by removing waste products from the central nervous system (e.g. spinal cord and brain). This is achieved, in part, by the exchange of solutes or waste products between cerebrospinal fluid (CSF) and interstitial fluid (ISF).

The system is comprised of a series of channels which appears to “piggyback” off blood vessels within the brain. It is argued that the movement of arteries, as a result of blood-flow, helps to move the cerebrospinal fluid through the brain (CSF). This enables the movements of waste between interstitial fluid (ISF) which bathes cells and CSF which runs alongside blood vessels in the brain. However, the glymphatic system also includes the presence of specific glial cells, known as astrocytes, alongside these channels. The function of the astrocytes is to facilitate the movement of particles between CSF and ISF. Without their presence, the movement of waste would be too sluggish to respond appropriately to the changing demands of the hungry organ we call the brain. It is the presence of glial cells, and the similarities to the lymphatic system, which give this glymphatic system its name.

Waste Disposal While You Sleep

How does all of this relate to sleep? Well, a recent collection of studies has provided some evidence that sleep may facilitate the movement of toxins from the brain via the increased activity of the glymphatic system.

One particular toxin produced as a waste product of brain cell activity is called amyloid beta. This toxin is linked to severe progressive diseases such as Alzheimer’s, and there is considerable research trying to work out how to mitigate its destructive effects. Last year, a group of scientists lead by Professor Maiken Nedergaard at the University of Rochester Medical Centre found that the brain’s drainage of amyloid beta was increased during sleep and anaesthesia-induced unconsciousness compared to during wakefulness in mice. More specifically, it seems that the capacity of the brain to flush out such harmful toxins is enhanced due to the area between cells, interstitial space, expanding by as much as 60 per cent. This seemingly enables a greater opportunity for such toxins to be removed via the glymphatic system.

In addition, the same group also found earlier this year that this process of washing harmful toxins out of the brain during sleep is enhanced based on the position of the mice studied. It was found that the removal of amyloid beta was enhanced when the mice slept on their side rather than their back. Interestingly, in both cases, it seems that anaesthetised mice showed the same effects as sleeping mice for the removal of amyloid beta and benefit of sleep posture.

This suggests that sleep may help with the maintenance of our brains by enhancing the waste disposal system we have in place. It may also provide some evidence as to why dementia and serious psychiatric illnesses are associated with sleep disturbances prior to the emergence of symptoms. However, this is all speculative and uncertain at this point. For a start, these studies have only been conducted on mice, and due to the nature of the experiment it is not likely that they would be conducted on humans any time soon. That’s not to say that the same mechanism might not be occurring within humans, but it is rash to jump the gun and assume it is.

Regardless, it will be exciting to see how research in this area advances and what it can teach us about the importance of sleep.

Inquisitive Tortoise

References:

Lee, H., Xie, L., Yu, M., Kang, H., Feng, T., Deane, R., … & Benveniste, H. (2015). The effect of body posture on brain glymphatic transport. The Journal of Neuroscience, 35(31), 11034-11044.

Xie, L., Kang, H., Xu, Q., Chen, M. J., Liao, Y., Thiyagarajan, M., … & Takano, T. (2013). Sleep drives metabolite clearance from the adult brain.science, 342(6156), 373-377.

Further Reading:

https://www.urmc.rochester.edu/labs/Nedergaard-Lab/projects/glymphatic_system (From the horse’s mouth; a better description of what I’ve tried to convey in this post!)

Image Credits:

Header image

Leave a comment

Filed under Psychology, Sleep Science

Sleep Trackers: Do They Work?

Main Pic

“What makes a good sleep tracker?”

“I didn’t sleep too well last night, and I felt so groggy this morning”

“Stressful day at work?”

“No, my stupid SleepApp didn’t work properly and I spent the night trying to get it to play relaxing whale noises. When I did drift off by myself, it didn’t wake me up in between sleep cycles. It better not fail tonight, I’ve got an important meeting tomorrow and I can’t sleep properly without it…”

“Uh-huh…”

Stilted conversation aside, we spend a large amount of our daily lives glued to screens of some description. These keep us active and engaged well beyond the time when we should be switching off for the night. For example, light from phones and laptops can alter our normal patterns of sleep and make it harder for us to drift off in the evening. This plays havoc with the body’s multitudinous clocks which naturally set in motion a number of chemical changes that allow us to unwind steadily before we drift off to sleep. However, that’s a point for another day.

For now, I want to talk about how we use technology to seemingly help us get to sleep and to, in want of a better way of putting it, tell us that we were in fact asleep the previous night (with or without a pretty graph to go with it).

Commercial ways to assess sleep:

There were two main ways of objectively measuring sleep in the research community: actigraphy and polysomnography (See what makes a good sleep tracker?) However, the business world has managed to split this up into a large selection of methods to tell us whether we’re sleeping enough. It may be that these different commercially available devices and apps are actually pretty good but the available evidence tells a different story.

Types of Sleep Tracker

I won’t go into too much detail about all of the different types of sleep tracking devices, of which there are many, but the purpose of the below list is to show the range of ways you can measure your sleep outside of the lab.

Movement-Based

Sleep apps developed for use on phones (e.g. Android or Apple stores) vary in cost and features which they promise. A popular sleep app for android users, ‘Sleep as Android’, has over 10 million downloads and boasts the ability to differentiate between wakefulness, light sleep and deep sleep. It also claims that it can wake you up during your lightest sleep stages in the morning to promote a “natural” awakening which supposedly avoids the grogginess and tiredness of waking up in the deeper stages of sleep. This app, amongst others, relies on movement-based information.

Movement-based trackers can also take the form of watches which track our sleep (alongside activity, exercise, and heart rate). Both of these aim to give us lots of detail about our sleep and provide us with statistics which try to educate us about our own sleep – mainly with the intention of helping you sleep better. These works by applying an algorithm to movement data which is logged by something called an accelerometer. This is already present in your mobile phone and the app simply makes use of this data to predict your sleep.

Brain-activity Based

There are a number of devices which you can buy which will offer a rudimentary attempt to track brain activity. Typically, if you want a good picture of your sleep you will track a wide range of different bodily functions in something known as polysomnography (see what makes a good sleep tracker?) However, these trackers try to track sleep through the use of a couple of electrodes placed on the scalp during sleep.

Temperature / Heart Rate / Muscle Response Based

Typically, these will be used alongside movement data to attempt to give a more accurate estimate of sleep.

Bed-Based

Again, these are technically based on movement and temperature data but are placed on the bed in some respect and not worn. These can take the form of a bed covering (link), or even a trendy looking ball such as Sense.

What makes a good sleep tracker?

So what does an ideal measurement of sleep look like?

Polysomnography

The gold-standard measure of sleep is known as called polysomnography. This measures a number of different things including:

  • Electroencephalogram (EEG; records electrical activity produced by cells in the brain)
  • Electrooculography (EOG; records eye movements)
  • Electromyography (EMG; records electrical activity generated by muscle activity)
  • Cardiac rhythms (ECG)
  • Respiratory activity

This setup, understandably, requires you to come into a sleep laboratory and sleep in a rather unfamiliar bed with electrodes planted on your head and body. This enables sleep researchers to record brain activity, eye movements, muscle activity and heart rhythms. Together, these readings allow us to identify how long you sleep, how often you wake up, how long it takes for you to get to sleep, when you wake up, and to identify the individual sleep stages and cycles which make up a normal night’s sleep. There are problems with this approach but it is the best option we have for understanding more about an individual’s sleep. As you’ll likely agree, this is a lot of information to obtain and wade through. Sleep apps and watches cannot possible recreate this and so are limited, but this is not necessarily a problem if they correlate well with other less rigorous but well accepted measures used in sleep research.

For example, most sleep apps and watches work by determining how often you move on a given night and use the times you are moving less as sleep and the times you are moving more as awake. These devices measure movement by using a little device called an accelerometer which is found within your smartphone and watches such as the FitBit.

Actigraphy

Within sleep research, we also use a device which is based on this same technology. The device is known as an actigraphy watch and it is generally seen an acceptable alternative to sleep lab measurements which are often costly, time-consuming and cumbersome. An actigraphy watch is usually worn on the non-dominant wrist, can be used outside a sleep lab, and thus allows researchers to assess sleep objectively as people go about their normal day-to-day lives. Actigraphy also works by detecting movement through accelerometers, and algorithms are applied to this data to explore certain facets of sleep (there are limits to this) in a more portable format.

Do these sleep apps actually work?

The main question you’ve probably come here to hear answered. The short answer: yes, but there are limitations to them all.

Quite simply put, there is a lack of research conducted here and the sample sizes are miniscule at best for the ones that do currently exist. Yet, these research studies do hint that perhaps sleep apps and wearable devices are actually assessing your levels of sleep in terms of duration, sleep efficiency and how often and for how long you are awake during a night of recording.

When sleep researchers try to determine whether wearables are actually tracking sleep they look for the following things: sensitivity (e.g. the ability of the app / device to measure when you’re actually asleep), specificity (e.g. the ability of the app / device to measure when you’re actually awake) and accuracy (e.g. is it measuring when you’re truly awake and truly asleep).

What does the current science say about commercial sleep trackers (e.g. FitBit)?

Wearables, or commercial sleep trackers, tend to show the same pattern when it comes to estimating our sleep patterns as that which is seen in actigraphy. Wearables using movement data typically overestimate total sleep time and sleep latency (how long it takes you to fall asleep) but are generally pretty accurate at telling when you’re asleep and for how long. By contrast, wearables such as the FitBit are poor at identifying periods of wakefulness during the night and will significantly underestimate disruptions in the night – known as wake after sleep onset (WASO). So, for the average person it is fair to say that wearables such as the numerous reincarnations of the FitBit may give you some insight into what your sleep looks like. However, if you are prone to fitful sleep or suffering from insomnia then these apps will be less accurate (despite claims on FitBit’s website that they may have a fix for people with disrupted sleep) and should not be depended upon. This is doubly the case if you consider using these in lieu of a going to a doctor about your sleep issues.

How about the claims made by, worryingly, many sleep apps and wearables that they can track different stages of sleep? The bold claim that a sleep app can measure REM sleep, for a start, is simply not known and extremely doubtful, even if some apps do add in more than just movement measures (e.g. heart rate). Other wearables such as the Jawbone UP make more reasonable claims that they can detect “light” versus “sound” sleep over a given night. Although it’s not entirely clear what “sound” sleep actually means, one research team took this to mean deep sleep and examined whether there was any truth behind this claim. In a large sample of adolescents, they found that the light and sound sleep measures were rather poor at measuring what they claimed to. Rather worryingly the ‘light’ sleep was found to be associated with time spent in the deepest stage of sleep which highlights that healthy skepticism should be applied to apps claiming they can pick out individual, or broad, sleep stages (see further reading).

Further Reading

A study by de Zambotti and colleagues examined the sensitivity and specificity of a different wearable, the Jawbone UP, compared to polysomnography and actigraphy in a group of middle aged women (average age 50 years old). They found, like others, that the Jawbone UP was generally accurate at determining when and for how long participants slept (but overestimated this value), but was pretty poor at determining when participants woke up during the night (underestimated this value, so had a good sensitivity but poor specificity). The ability to detect periods of waking and total sleep during the night were notably bad during particularly disrupted sleep as detected by PSG. This suggests that the Jawbone UP and FitBit Ultra are not particularly accurate at detecting the amount of sleep and waking in individuals with disrupted / fragmented sleep.

When the same research group (de Zambotti et al., 2015b) also examined the Jawbone UP in a sample of adolescents and young adults (age range 12-22 years old) and found similar results. That is, that the Jawbone UP overestimated total sleep time, sleep efficiency and sleep onset latency but underestimated total wake time during the night (it was much worse at detecting time spent awake than any of the sleep measures). Overall, it was found that the Jawbone UP was good at detecting when participants were asleep, but rather poor at identifying when they woke up during the night. This is important as fragmentation of your sleep will impact on sleep quality.

The same study also tried to examine whether the Jawbone UP’s dichotomisation of ‘sound sleep’ versus ‘light sleep’ were appropriately linked to deep versus light stages of sleep as assessed in the sleep laboratory. The ‘light sleep’ count was linked to movement and awakenings, and also to stage 3 of sleep (known as the deepest stage of sleep). In fact, none of the lightest stages of sleep were shown to be associated with the ‘light sleep’ count produced by Jawbone UP. The opposite was found for the ‘sound sleep’ count whereby typically deep stages of sleep were not found to be associated with this measure, but rather overall measurement of movement (specifically reduced movements) was. This suggests that wearables such as Jawbone and FitBit may be reasonable at detecting sleep during the night, but not night-time awakenings or the different stages of sleep. Furthermore, in populations where sleep is fitful or fragmented the accuracy of these apps reduces to a greater extent.

A previous study by one of the study’s authors, Hawley Montgomery, in 2012 found that a wrist-worn FitBit was comparable to actigraphy, but poorer than polysomnography in detecting when people were asleep. However, the FitBit was particularly poor in identifying when people woke up compared to actigraphy. This suggests that the healthy adult populations could still gain useful information from a FitBit but, as the authors highlight, it is a far way off being appropriate for measuring sleep in people with diagnosed or suspected sleep disorders.

As you can hopefully see, there are only a handful of studies which have attempted to understand how good market-leading wearables are in detecting sleep and wake. The emphasis on sleep and wake is intentional. These apps have not been assessed for their ability to assess anything beyond total sleep time, wake after sleep onset, sleep onset latency and sleep efficiency.

Smart Alarms

Other sleep apps also include a measure to wake individuals up during the lighter stages of sleep to enable them to feel more wakeful in the morning. The alarm sounds after tracking an individual’s pattern of sleep to create an ‘optimal’ window to wake up during which the alarm will try to target. Alarm PicHowever, there is currently limited evidence to back up these claims (Kelly et al., 2012), and there needs to be considerably more research here before such claims can be validated and backed up (SLEEPIO Article). It is somewhat surprising that such research has not been carried out considering how easy it would be to create an experiment where participants are randomized to either an optimal or sub-optimal wake-up alarm condition over 1-2 weeks (See Kelly et al., 2012 for expansion on this very point).

Concluding Thoughts

Sleep is something which can be fickle at many times throughout our lives, and it is not surprising that we would want to learn more about it. However, for those of us who suffer with our sleep on a regular basis, there is an obvious appeal to be able to track our sleep in the comfort of our own homes and on a regular (perhaps even nightly) basis. It may provide a skewed notion of how an individual is sleeping (for better or for worse) and this can provide unfounded alarm or comfort. The current wearables have a reasonable ability to tell when and for how long you’re asleep but be sceptical on their ability to tell you anything about the quality of your sleep. If you are genuinely concerned about your sleep then please consult your doctor.

Sleep apps, wearables and other sleep trackers are a fantastic idea and if they can prove to be comparable to other methods such as actigraphy then I see few reasons to discourage their use. However, there is a lack of available data to really understand whether these different sleep trackers are accurate. If they are simply measuring time spent asleep and awake then they seem to be okay, and comparable to measures used in sleep experiments. Yet, bolder claims about smart alarms, tracking individual sleep stages, and their use in sleep disorders are not conclusively studied at this moment in time. That is not to say they will not, but there is a sensible reason to be cautious until that evidence is available to us. So, by all means use these trackers and add them to part of your daily routine if you so wish. However, understand their limitations and be aware that paying minute detail to your sleep may also create its own problems. More on that point in my next post.

Inquisitive Tortoise

References

de Zambotti, M., Baker, F. C., & Colrain, I. M. (2014). Validation of Sleep-Tracking Technology Compared with Polysomnography in Adolescents. Sleep, 38(9), 1461-1468.

de Zambotti, M., Claudatos, S., Inkelis, S., Colrain, I. M., & Baker, F. C. (2015). Evaluation of a consumer fitness-tracking device to assess sleep in adults. Chronobiology international, 32(7), 1024-1028.

** Kelly, J. M., Strecker, R. E., & Bianchi, M. T. (2012). Recent developments in home sleep-monitoring devices. ISRN neurology, 2012. (Good expansion on the different sleep trackers available)

Montgomery-Downs, H. E., Insana, S. P., & Bond, J. A. (2012). Movement toward a novel activity monitoring device. Sleep and Breathing, 16(3), 913-917.

Montgomery-Downs, H. E., Insana, S. P., & Bond, J. A. (2012). Movement toward a novel activity monitoring device. Sleep and Breathing, 16(3), 913-917.

Further Reading

http://www.huffingtonpost.com/dr-christopher-winter/sleep-tips_b_4792760.html

https://www.sleepio.com/articles/sleep-aids/sleep-apps/

Image Credits:

Main Pic

Alarm Pic

Leave a comment

Filed under General Interest, PhD, Psychology, Sleep Science

How Much Sleep Do We Need?

5185437718_fc019d085f_z.jpg

Despite our urge to squeeze everything out of the day, sleep is something we cannot live without.

As I start to think about this question, I can feel the inner scientist in me asking a range of questions in response to your first. Sadly, I have a limit to how long my response should be before people start turning off… So, to prevent his becoming a short thesis in itself (or several), I have opted to approach this question in terms of a healthy adult and to focus on how much sleep we need to remain physically and mentally healthy, and not just simply survive.

It is important to ask how much sleep we really need, and just as important to make sure we actually try to achieve this. As we’ll see, sleep is vital for the healthy functioning of many physiological and mental faculties that to skimp on it is inexcusable. As I type this, I can hear many crying out “modern living”, “deadlines”, “fitting everything in”, and even the faint whispers of “YOLO” on the breeze. However, sleep is not simply an inconvenience to our daily lives but an important part of keeping us functioning.

To highlight this, let’s look at the effects of a lack of sleep. A chronic lack of sleep has been shown to be associated with heart disease, type 2 diabetes, and stroke to name but a few. It should also be noted that there’s such a thing as ‘too much’ of a good thing, as excess sleep is associated with similar problems as too little sleep (Shen et al., 2016). At some point, you have probably felt the effects of lying in for too long and the scourge of ‘sleep hangovers’.

How do we measure an ‘optimum’?

There are a number of ways we can do this, but first we need to understand what we mean by optimum and why we sleep in the first place. The exact function of sleep is still not fully understood but it is generally agreed that sleep enables us to grow, is vital for memory and keeps us alert and healthy. In fact, prolonged durations without sleep can distort our perception of reality, interfere with our memory in a staggering way and, in very extreme cases, lead to death.

By looking at this in the long-term, we can identify the ‘optimum’ amount of sleep by observing lots and people’s sleep habits and to identify the risks associated with differing hours of sleep. We can also deprive individuals of sleep and see how they function after a couple of hours (or complete) sleep restriction compared to a normal night. For example, if we deprive someone of 1 or 2 hours sleep per night do we see any effect of an individual’s ability to function during the daytime? If the answer is yes, then this would suggest that those extra hours of sleep are important to us in some way.

So, we are now more familiar with why we should attempt to get the right amount of sleep, and how to measure the importance of sleep, but how much do we actually need? The simple answer is that 7-8 hours is generally considered to be ideal for the majority of individuals. A recent study highlighted that 7 hours was optimum for avoiding the negative impacts of too little or too much sleep (Shen et al., 2016). Another comprehensive review highlighted again that between 7-8 hours was optimum when considering all-cause mortality (i.e. your chance of death is reduced if you get between 7-8 hours of sleep a night, when compared to more or less sleep).

What about those who can survive with less than 7 hours?

However, although there is some merit in this claim, it has created the idea that there is a ‘perfect’ amount of sleep, and that this is the same for everyone. This really is not the case and the amount of sleep an individual ultimately needs to feel refreshed and to function varies from person to person. To many sleep scientists this is source of frustration and avid fascination. Take, for example, individuals who only need 5-6 hours of sleep a night to function, and those who claim they can get by with even less.

Why might it be that some people need less sleep than others? The simple answer seems to be that it all lies in our genetics, and certain mutations in our genetic code are linked to a greater resistance to the effects of sleep deprivation. A particular set of gene mutations outlined by Pellegrino and colleagues (2014) was associated with a reduced need for sleep and fewer negative effects associated with reduced sleep (6 hours). They established that a reduced need for sleep, or an increased resistance to sleep loss, is heritable and the genes involved seem to impact the internal clocks we have in every one of cells.

8372546412_f9eb757eba_z.jpg

“Sleep is not simply an inconvenience to our daily lives but an important part of keeping us functioning.”

Yet, there is a problem with these studies, and others which have looked at those resistant to sleep deprivation. Some individuals may be resistant to effects of sleep deprivation on attention and day-to-day functioning, but most of the large sleep studies have focused on the health impacts of sub-par sleep over very long periods of time. These ‘sleep-deprivation resistant’ studies are conducted over the course of a couple of weeks; the long-term impact of sleeping less than 7-8 hours, and being resistant to short term sleep restriction, has not be extensively studied.

Therefore, it is conceivable that individuals can go with less than 7-8 hours’ sleep in the short term, and some may be better than others at getting away with this. However, ‘getting away with it’ may be just the term we want to use here. These individuals may be able to compensate early on but still be prone to the same health issues associated with reduced sleep as the rest of us in the long term.

Effect of Chronotype

I am about to go off a seemingly unrelated tangent but bear with me (it’ll be interesting, promise!) When people think and talk about sleep in terms of what is optimum and healthy, they will often focus on the duration of sleep. Most people will also mention when they drop off and wake up, but a large part of this conversation will be in relation to their willpower and how they “should really go to bed earlier and wake up earlier”. However, when we go to sleep is an important factor to keep in mind as we look at what healthy sleep looks like. Each of us can be classified on the basis of something called a chronotype and this describes at what time we go to sleep and wake up on a typical day. Although people fall along a complete spectrum, and show some variability, there are two main camps which most tend to fall into: early risers and night-owls. As the names suggest, early risers go to bed earlier and wake up earlier than the night-owls who find themselves more productive later in the day and subsequently wake up later. Great, thanks for the information Jack, but why is this important for my further understanding of healthy sleep?

Although sleep duration is important for a healthy mind and body, the time at which our body wants us to sleep and rise will impact on whether we can achieve the right amount of sleep in the first place. Our current schooling and working world favours the early-risers. As a result, night-owls unfortunately have to constrain their normal sleeping patterns during the working week to fit with the demands of a 9-5 society. This is important, as night-owls may catch-up slightly on their sleep schedules during the weekend but this is rarely enough and produces what is known as social jet-lag. This is the mismatch between what our body-clocks are screaming at us during the week when we wake up earlier than we would naturally do so, and the extended sleep we have during the weekend to attempt to rectify this.

The attempt to rectify the sleep-debt during the weekend is not enough, and this is highlighted by the increased prevalence of mental illnesses in those who score as night-owls on chronotype measures. Therefore, when as well the duration of sleep is important when we consider what healthy sleep should look like. Granted, altering the duration of sleep might be simpler to achieve for most of us than being able to get up later, but that does not make ignoring our own sleep rhythms any less important.

So, although I could likely go on for much longer, I should leave it there. The take home message is that 7-8 hours is the ideal duration of sleep required for a healthy existence. We should also be mindful that duration is not the only indicator of healthy sleep, and listening to your own sleep rhythms is important to ensure you get sufficient and good quality sleep.

Afterword

So,  I have to admit that the inspiration for this question came not from me directly. In fact, the question was part of a project which is collecting an increasingly large database of questions about science in general. The project, known as The Science Room, is run by a good friend of mine in Southampton, and it is determined to answer everyone’s science questions (ambitious, I know!) On that note, if you’re interested in asking any science based questions or learning more about the project, you can find the current webpage here: http://thearthousesouthampton.org/the-science-room/

The answer to this particular question is due to appear on a website dedicated to answering all of these questions (amongst many other things!) I shall link that site here when it’s complete.

Inquisitive Tortoise

Image Credits:

Header Image: Exhaustion

Second Image: Clock

1 Comment

Filed under Media, PhD, Psychology, Sleep Science

BBC’s ‘In the Mind’ Series

Television

I haven’t written anything in a little while but hopefully that should be fixed over the next week (workload depending). Anyway, this brief post is a slight departure from the normal foray in sleep and everything related to it. I wanted to bring people’s attention to the series of mental health documentaries, short films and portrayals of serious mental illnesses been shown on the BBC over this month. You can find a summary of all of the programs which have already been aired, and are yet to be aired here: http://www.bbc.co.uk/mediacentre/latestnews/2016/in-the-mind

The hour long documentaries / films follow people who have suffered from mental illness in some form of another and create a narrative for the viewer to follow. The aim is to educate and through this hopefully reduce the stigma surrounding in general.

It’s great to see that these documentaries have tackled issues which receive less attention in the media such as postpartum psychosis and bipolar disorder. The former is a disorder which I frequently come across in my reading but which I had no real understanding of. Although an hour is hardly enough to really get to grips with how these disease manifest and impact on a wide variety of different peoples’ lives, the documentaries on biplolar disorder and postpartum psychosis do provide us a privileged window into the lives of people, and their loved ones, fighting with mental illness. Admittedly, it is hard to watch certain scenes and it personally brings back familiar experiences from my own family, both as a child and as an adult.

Also, if anyone is interested, Prof. Richard Bentall has given his own opinion on the BBC’s depiction of bipolar disorder as primarily a biological disorder (https://blogs.canterbury.ac.uk/discursive/all-in-the-brain/#.VscA52Zud_U.twitter) He acknowledges the role of drugs in the recovery of very ill individuals but argues that a focus on the biological aspect of mental illness does very little to help with stigma (e.g. it creates a dichotomy of the sick and the healthy). I agree in the sense that the documentaries I have managed to watch so far focus on the severe stages of mental illness and neglect the broad spectrum of mental illness from health to hospitalisation. They give people a glimpse into mental health but perhaps see it as if through a window into the ‘other side’. However, I would also argue that these documentaries give understanding of what it means to be given a diagnosis of a mental illness and how individuals and their families deal with this. In this sense, they help to break down boundaries between stigmatised terms, such as ‘psychosis’, with no human experience to attach to them. It is because of this I would suggest people watch at least one of the documentaries being shown and currently on iPlayer.

Anyway, I just wanted this to be brief and not a matter of me typing lots of stuff into the ether of wordpress. One last thing, I also want to give a link to a really useful link about the role of drawing in talking and dealing with mental health (here http://www.bbc.co.uk/newsbeat/article/35564616/mental-health-week-how-drawings-on-social-media-are-changing-the-conversation?ocid=socialflow_facebook&ns_mchannel=social&ns_campaign=bbcnews&ns_source=facebook) Although her work isn’t included here but I personally found the drawings of Allie Brosh particularly helpful and a good explanation of what it is to live with depression (http://hyperboleandahalf.blogspot.co.uk/2011/10/adventures-in-depression.html). Please check some of these out, and share them with people who might find them helpful, educational, or simply interesting.

Inquisitive Tortoise

Leave a comment

Filed under Media, Psychology, Schizophrenia, Voice Hearing

Sleep Snippet: Why Bother Even Trying to Understand Sleep?

157020281_aa2d64877f_o.jpg

Sleep in its natural environment.

It’s a fair question (although don’t tell my supervisors that I said that…) We enjoy doing it, it refreshes us, and we tend to find ourselves doing it in any spot we find ourselves last thing on a Wednesday afternoon. Most of us could identify that we need sleep and that it helps maintain the brain and body in some way but why do we need to go any further than that, other than for pure curiosity?

Sleep is important for our ability to function in the world about us. As we are likely all aware, a night without sleep or a few days with very little sleep can make it incredibly hard to do much of anything. We find it hard to concentrate on conversations with colleagues or friends, find ourselves becoming more forgetful and start to see every nook and cranny as ideal spots for a quick nap. In addition, we become more irritable and may find it harder in general to control our emotions. If we have been deprived of sleep for long enough, we may even start to see and hear things which are not really there and become increasingly paranoid.

For most of us these experiences are temporary and we can largely shrug off the negative effects of too little sleep by making sure we go back to a regular routine of sufficient sleep. However, what about those who can’t? What about people who struggle to sleep at all and who do not feel rested after a night in bed? It is important to understand a) why these individuals struggle with sleep and b) how poor sleep leads them to experience the negative side-effects we all do but to a much greater degree? The second question, in part, can be understood by trying to explore the effect of a lack of sleep on relatively healthy individuals like you and me.

The importance in understanding why we sleep and how this should look in the brain lies in how we can use that knowledge to help those who can’t sleep or whose sleep is disturbed significantly. This can involve those who suffer from sleep disorders such as insomnia (where we don’t sleep enough), hypersomnia (where we sleep too much), and narcolepsy (where we unexpectedly fall asleep throughout the day) to name a few examples.

We can also look at the role of sleep difficulties in the context of other illnesses, where problems drifting off to sleep and staying so can exacerbate or lead to many different symptoms of disease. For example, sleep difficulties have been implicated in many mental illnesses such as schizophrenia, depression and anxiety disorders. In fact, around 80% of individuals with schizophrenia will experience some form of sleep disruption. Sleep difficulties have also been shown to have an influence on diseases of the immune system such as ulcerative colitis, psoriasis, and in neurological conditions such as Parkinson’s disease. I am very conscious of how many different disorders I could list where an understanding of sleep could help to reduce suffering but that might make for a rather boring article (and not help with my self-imposed word limit…) Through understanding sleep, we can understand these related illnesses to a greater extent and hopefully provide better treatments for patients.

Hopefully, in this short snippet of an article has shown that understanding why and how we sleep is important and worthwhile.

Inquisitive Tortoise

Image Credits:

Header Image: Sleep in Society

Leave a comment

Filed under General Interest, PhD, Psychology, Sleep Science