Category Archives: Psychology

Should We Start Drinking Cherry Juice To Improve Our Sleep?

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Should you start drinking cherry juice to boost your sleep?

The internet is awash with advice based on rubbish science, and it’s not unusual for news outlet to pick up on this. Luckily, I have a source who expertly scours the internet and provides me with the best of the worst scientific journalism. Today’s offering is from the Daily Mail who are advertising the miraculous sleep inducing powers of tart cherry juice and other shady sleep treatments. The article in question claims that you can get 84 extra minutes of sleep if you start drinking tart cherry juice. Seems too good to be true? Well, let’s take a look at the research in question.

This study was led by Jack Losso at Louisiana State University. His team had a group of 8 people take part in a pilot trial of whether tart cherry juice would improve sleep in a group of individuals diagnosed with insomnia. The participants in this trial were initially randomised to either drink a cherry or placebo drink twice a day (once in the morning and once again a few hours before bed). Their sleep was assessed at the start of the study and again two weeks later at the end of each stint of juice or placebo. They found that the participants spent 86 more minutes asleep in the cherry juice compared to placebo condition. Additionally, out of five self-report sleep measures there was found to be an increase in sleep efficiency (time in bed divided by time spent asleep) as measured by only one of these.

Unfortunately, this study is not available online, so we only have access to the abstract and the press release until it is published September 2018. This makes it hard to analyse in any more detail. This was a very small pilot study with only 8 participants diagnosed with insomnia. In addition, the study threw a lot of different sleep questionnaires at the trial for little plausible reason other than they could. It’s not unusual for there to be two (different measures assess slightly different things) but five is overkill. This is worrying as it suggests that the researchers could change the goal posts if one measure did not produce the effect they wanted to see.

The Daily Mail articles also seems to have glossed over the age of the participants who were “over 50” according to the study. This study alone is not enough to convince us that cherry juice is something we should all stock up on to combat a poor night’s sleep. However, what is the wider evidence to support cherry juice impact on sleep?

The initial rationale for conducting these trials was based on a mixture of anecdotal evidence and plausible biological pathways. For example, it has been suggested that tart cherry juice can reduce inflammation and increase melatonin levels. Both of these could conceivably improve an individual’s sleep. However, prior to this recent pilot trial there was very little scientific research to support an association between improved sleep and tart cherry juice. Based on my own search of the literature, there were two additional published trials I could find which looked at the effect of tart cherry juice on sleep.

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The evidence for cherry juice and sleep is currently lacking

The first by Glyn Howatson and colleagues recruited a sample of 20 people with a mean age of 27. In this study participants were either given diluted tart cherry juice or a placebo fruit cordial. The participants were not told about the hypotheses beforehand, but I’m still not entirely convinced that people wouldn’t have cottoned on to what drink was supposed to be doing something. The researchers found no differences in sleep when they looked at the self-report measures except a reduction in napping from 9 minutes to 2 minutes in the cherry juice group. Participants in the cherry group did stay in bed slightly longer and spent longer asleep (34 minutes) as measured by a Fit-Bit like watch. Of course, if they were spending longer in bed, immobile, it is perhaps not surprising that their sleep would have been longer too due to limitations of such devices (e.g. they treat a lack of movement as sleep).

The second study by Wilfred Pigeon and colleagues conducted another pilot randomised controlled trial with 15 people who were, on average, about 72 years old. It used a similar setup as Glyn Howatson’s randomised controlled trial in that participants were randomly assigned to drink either the placebo or cherry juice first. The other drink was then given two weeks later. Their ‘cherry juice’ was actually a blend including both tart cherries and apple juice which makes it hard to say that it was the cherry juice specifically having the active effect. In this study, using self-report sleep diaries, it was found that participants went to sleep 2.6 minutes quicker, slept 8.4 minutes longer, and spent 17 less minutes awake during the night in the juice (cherry and apple) compared to the placebo juice drink. A fuller exploration of this study can be found here on the brilliant NHS Choices website but again, this study is far from convincing.

Together, these studies are not poorly conducted but their findings are not particularly impressive either. They do suggest that cherry juice may be doing something but it’s hardly comparable to the supposed 84 minutes which leads the Daily Mail article. In fact, the second study, besides having a tiny effect on sleep, is not even solely cherry juice. Personally, I don’t have the option to get 85 extra minutes sleep, I’m more interested in my sleep being more restful. None of these studies showed that this was the case and this is something which is likely to be more important to most people including those with a diagnosis of insomnia.

Finally, because you can’t make this kind of stuff up, two of these three studies were part or fully funded by the Cherry Marketing Institute. The only study that wasn’t funded by them was given free products by a company which produces and sells, including other products, cherry-based drinks aimed at physical enhancement. It’s not unusual for an intervention to have a hand in a trial but this, and the Daily Mail article, feels more like advertising than validating a potential treatment. Is it too much to ask for a randomised controlled trial without some form of cherry PR company hovering in the background?

With all of this in mind, cherry juice’s effect on sleep does not seem to have a scientific basis. As always, if you find tart cherry juice is a miracle cure for you then feel free to ignore me. Your glass of tart cherry juice is hardly causing anyone harm and it’s fantastic if, anecdotally, it works for you. However, in this instance, it looks like cherries are another alternative treatment for insomnia which need to be taken with a considerable bucket full of salt.

I never liked cherries anyway.

Inquisitive Tortoise

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References

Losso, J. N., Finley, J. W., Karki, N., Liu, A. G., Prudente, A., Tipton, R., … & Greenway, F. L. (2017). Pilot Study of the Tart Cherry Juice for the Treatment of Insomnia and Investigation of Mechanisms. American journal of therapeutics.

Howatson, G., Bell, P. G., Tallent, J., Middleton, B., McHugh, M. P., & Ellis, J. (2012). Effect of tart cherry juice (Prunus cerasus) on melatonin levels and enhanced sleep quality. European journal of nutrition51(8), 909-916.

Pigeon, W. R., Carr, M., Gorman, C., & Perlis, M. L. (2010). Effects of a tart cherry juice beverage on the sleep of older adults with insomnia: a pilot study. Journal of medicinal food13(3), 579-583.

 

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Filed under Debunking Headlines, Psychology, Sleep Science

Biphasic Sleep: Should we stop sleeping in a single, uninterrupted, block?

 

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“What’s the right amount of sleep I need? Should I be drinking cherry juice to sleep better? Why do you keep ignoring my voicemails?”

In the absence of being asked about dreams, people are generally keen to hear my views on how to get the best sleep possible. I think this is a fair question to ask a sleep scientist. I’m less convinced that you’ll get an accurate answer from a mattress salesman – but maybe that’s just me. A normal night’s sleep typically involves a single block from the moment our heads hit the pillow to when we feel our way towards our phone alarm in the morning. The number of hours sleep will vary but this will probably be somewhere between 7 to 9 hours (it may be slightly more or less than this). Hopefully, you’ll also feel fairly refreshed after waking up. Many of us still feel tired the following day for a myriad of reasons and will seek some solution for how to feel more energetic, creative and productive. One sleep buzzword which has attracted many such sleep perfectionists is ‘biphasic sleep’ and it involves splitting up our usual undisturbed bout of sleep.

For some people, sleep is experienced as two (or more) bouts of slumber throughout a night. For these biphasic sleepers, they will enjoy an initial sleep followed by a period of wakefulness and then finish off the night with their second sleep. Unlike those of us who restlessly wake up in the middle of the night and feel awful the following day, biphasic sleepers feel fully refreshed with their fragmented pattern. Some natural biphasic sleepers can even mistake their wakefulness for insomnia and this can cause its own problems.

There is some evidence that biphasic sleep is everyone’s normal sleep patterns but artificial lighting has forced us to sleep in one undisturbed bout. However, the scientific evidence to back this up has been somewhat sluggish. It wasn’t until late into the 20th century that our capacity for a biphasic sleep schedule was brought to light.

In the early 1990s, the psychiatrist Thomas Wehr showed that individuals under strict lighting conditions shifted from a single block of sleep to sleeping in a more segmented fashion. In his sample of eight healthy white men, Wehr had them spend 4 weeks under ‘winter’ lighting conditions whereby they had 10 hours of light a day. Then, as a comparison condition, the participants were exposed to 16 hours light and 8 hours dark to broadly mimic summer lighting for a single week. Under summer lighting conditions, the participants slept in one single block and appeared to be largely consistent in their sleeping patterns. However, when they were required to spend a month in the winter lighting pattern, they showed fragmented sleep that was typically, but not always, split in two or more segments (e.g. biphasic). This suggests that provided the period of darkness is long enough, such as experienced during the winter months, then the sleep period will start to be split up over a typical night. As a result, advocates of biphasic sleep as the optimum sleep schedule frequently quote this study as concrete evidence for their point of view.

It’s important to note a few things about this commonly referenced study. In the ‘winter’ condition, participants were told they could do not do anything active during the dark periods (e.g. listen to music or exercise). They were not allowed to use artificial lighting and were encouraged to rest during the dark period. This didn’t leave much choice but to sleep during this 14-hour window. Therefore, biphasic sleep might be seen because the participants had nothing better to do than go back to sleep if it was still dark upon awakening.

This was the same conclusion put forward by a study published in 2015 which also argued that a switch to biphasic sleep may simply be a result of long winter nights. Not everyone agrees so readily with this interpretation. However, until more convincing research is forthcoming it looks like we shouldn’t be trying to wake ourselves up at 2am every morning for that mid-sleep conference call. There is no evidence (as always please try to prove me wrong) that splitting your sleep into two segments is better than sleeping in a single block. Current advocates of biphasic sleep tend to singularly use Wehr’s study as evidence for their points without acknowledging the caveats to his study.

So, that still leaves the question remaining why some groups are advocating splitting up your sleep into small segments if the evidence is lacking. Well, besides our obsession with being told exactly how much of everything (e.g. fruit, water, sleep, fun) we are supposed to have there is a common theme to those keen to split up their sleep – they want to sleep less. Madness, I know.

Terms such as biphasic and polyphasic are frequently kidnapped against their will to lend legitimacy to schedules such as Everyman and Uberman schedules. These sleep schedules aim to break the day into small naps so that people can work unhindered by something as trivial as sleep. To put this into context, the Uberman schedule involves sleeping no more than 2 hours broken neatly up into 6 separate 20-minute naps – sounds lovely, doesn’t it? Well… By contrast, the Everyman schedule allows you 3 hours of sleep followed by 3 naps of 20 minutes throughout the day. So, you get a whole 4 hours sleep with this approach. I will save why these schedules are ridiculous for another post, but I’ve included them to illustrate that interest in segmenting the night’s sleep overlaps considerably with ‘hacking’ the numbers of hours of sleep we need in a day.

As I’ve hopefully make clear so far, sleep is important – all of it. Hacking your sleep will leave you exhausted and at an increased risk for multiple physical and mental illnesses. If you’re interested in feeling more energetic, perhaps think about whether sleep really is the culprit. Alternatively, maybe stop reading these blog posts at 2am and sleep. Actually, on second thoughts…

Inquisitive Tortoise

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References

WEHR, T. A. (1991). The durations of human melatonin secretion and sleep respond to changes in daylength (photoperiod). The Journal of Clinical Endocrinology & Metabolism73(6), 1276-1280.

Ekirch, A. R. (2016). Segmented sleep in preindustrial societies. Sleep29 (3), 715-716.

Yetish, G., Kaplan, H., Gurven, M., Wood, B., Pontzer, H., Manger, P. R., … & Siegel, J. M. (2015). Natural sleep and its seasonal variations in three pre-industrial societies. Current Biology25(21), 2862-2868.

 

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

Twitter, chronobiology, Trump, and Questions You Didn’t Realise Needed Answering

Twitter

Tweets in their natural environment

Scientists are a weird bunch. We spend our lives getting very excited about niche and bizarre things. As a result we have a habit of spending our free time trying to get others to understand our excitement. There are also times when these strange topics align with the wider interests of the general population. For example, we may ask the big questions which are important and crucial for a functioning society.  However, there are also times when we wonder whether we can put to bed (pun fully intended) whether Donald Trump is a keyboard bashing night-owl or a keyboard bashing early riser. But you don’t want to know about that, right?

Well in case you do, luckily one rather eminent (and fun) chronobiologist felt that it was appropriate to answer that singularly important question. Don’t worry, we’ll come to why this is actually an important question later. Now, social media can be used to identify a lot about us and it is not that hard to use all of the data from platforms such as Facebook to track (loosely) a friend’s sleep. It also seems that social media can also be used to determine your activity patterns and assess biological rhythms besides sleep.

For anyone who has ever logged onto Twitter, you are probably aware of the late-night tweets of @realDonaldTrump and their varying levels of coherence. However, do these few late-night tweet fests correlate with the normal chronotype of the president? Firstly, what do we mean by chronotype? Chronotype is the term used to refer the times at which individuals tend to be awake and active. For example, you are probably familiar with the concept of morning and evening types. These relate to our internal body clocks and govern whether we are happy to work late or decide to retire early on. Although society seems to associate the early birds with success, there are issues when our body clocks do not align with the pressures of a society which is regimented and requires us to wake up at the set times – whether for work or school. In fact, there is growing and convincing evidence to suggest that delaying school start to fit with adolescent’s chronotype would be beneficial .

Typically, we assess chronotype through the use of questionnaires or by tracking activity of an individual over an extended period of time. Yet, how can we assess Trump’s chronotype if we can’t handily give him a detailed questionnaire or activity tracker? Simple, we mine his Twitter data and assess his activity based on tweets. Luckily for us, the current President likes to tweet – a lot. This gives interested researchers plenty of time points to assess how his activity changes over time.

Professor Roennenberg applied his analysis to 12,000 tweets from December 2014 to March 2017. Out of all these tweets, there were three main devices they were sent from: an android device, an iPhone device, and other miscellaneous devices. The majority of the tweets were from the android device and it was suggested that the android phone was likely Trump’s personal phone. With all of this rich data, it was possible to identify the peak tweeting periods and how these changed month by month over the 830 days of tweets analysed.

So, what was found? Well, contrary to expectations, it appears that Trump is actually a consistent morning type. There was a clear patterning in the peak times at which he was tweeting. There tended to be a peak in the morning between 5:10am-9:40am (around sunrise) and a peak in the evening 5:00pm-11:00pm (around sunset) that shifted through the year with the change in hours of sunlight. For example, during the summer months, Trump had peaks of tweets earlier in the day and during the winter months these were later during the day. This is a clear pattern of tweeting which fits seasonal changes in light levels.

By contrast, tweets sent from the iPhone showed peaks of activity between 8am and 4pm which highlights a mixture of working hours and staff activity. It was hard to assess circadian patterning using this account as it appeared that multiple people contributed to these data. The ‘MiscDevices’ showed peak activity during between 8.20am and 4.50pm which suggested that this was used during the working day. On the basis of this, the study showed that it is possible determine patterning of activity over a long period of time from tweet data alone. In this case, it shows the peak tweet activity for Donald Trump and in turn this allows us to determine (roughly) his chronotype and probable sleep period.

Why is this worth reporting on? Honestly, to begin with, it is hilarious. I love the author of this piece for taking a ridiculous question and applying the full force of the scientific process to it. Personally, I think this research should be considered for an IgNoble award. However, when you move past the fun of this piece it also highlights a powerful research tool. The use of social media data in research is increasing and there are some great and novel studies which have taken this approach. This method can allow us to, as in this paper, track the sleep, circadian and seasonality patterns of an account – provided it has sufficient data points. In this case, Trump was a perfect proof of concept. Moreover, this technique could also be used to not just track sleep patterns but also be mined for content. Roennenberg makes a quick allusion to the content of Trump’s early morning tweets but this approach has implications for research. This data mining of social media approach would enable questions to be asked not just about the patterning of account activity but also how this activity might be associated with, for example, mental health. To me this is an exciting tool which has considerable potential albeit with significant ethical concerns attached.

Until then we can use this technique to open a window into the life of the rather prolific tweeter that is Donald Trump. Now don’t tell me science isn’t tackling the big (so big) questions.

Inquisitive Tortoise

References

Roenneberg, T. (2017). Twitter as a means to study temporal behaviour. Current Biology27(17), R830-R832.

Berry, N., Lobban, F., Belousov, M., Emsley, R., Nenadic, G., & Bucci, S. (2017). # WhyWeTweetMH: Understanding Why People Use Twitter to Discuss Mental Health Problems. Journal of medical Internet research19(4).

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Can sleep loss induce a negative implicit bias towards Arab-Muslim names?

Racism

People suck. Well they certainly seem to after several nights without sleep. As the lost hours pile up, those simple things sent to try us become all the more difficult to face. We are generally just less able to employ self-control to moderate our feelings towards the outside world. I mean, it’s like Nigel Farage said to me down the pub once, we even tend to make racist comments when we’re a bit tired. Now sleep deprivation does not make you racist, despite amusing attempts to throw old Nige a bone, but it may be that a lack of shut-eye can make us less able to inhibit unconscious biases.

Unconscious biases are not necessarily a bad thing before we start to bash them. They allow us to employ speedy decision making without having to weigh up the pros and cons of a situation. When you’re faced with immediate danger you don’t want to spend time considering the difficult childhood of your knife wielding assailant for any more than a split second before you run away with your tail, and wallet, trailing behind. However, when we’re not facing a troubled mugger your conscious mind can step in and make use of available mental resources to stop yourself acting on your unconscious biases. This allows you to mask your own biases under the shield of social desirability. However, how do you assess an individual’s unconscious biases if they are unaware of them themselves?

It is possible to assess your unconscious biases by completing something called the implicit association test (IAT). This was developed by social psychologists Anthony Greenwald who wanted to try to understand the unconscious biases individuals held. They felt that explicitly asking individuals about sensitive issues was a poor way to investigate controversial topics as people would be likely to hide their true responses behind a ‘socially desirable mask’. Instead if you got people to respond very quickly to words paired with negative or positive emotions you could see how readily certain associations are recognised. For example, you could show pictures of white and black faces and pair them with positive and negative emotions. You could then present every possible combination in a randomised order (black-good, white-bad; black-bad, white-good) and see how quickly people respond to these pairings. The logic being that if you were quicker to respond to black-bad and white-good than the other pairings you, on an unconscious level, see these as more strongly related than the alternatives. Race is used here as an example but this task has been used for a wide range of different judgements such as gender and careers, weight, age and many others. You can see many of them and give the task a go here.

It should come as no surprise that sleep is considered important when it comes to our unconscious biases. Hopefully anyone who has read at least one of these posts should be aware of how many things sleep is important for. A study published in 2015 showed that by stimulating slow wave sleep (i.e. the deepest stage of our nightly slumber) you could enhance daytime training to reduce unconscious negative biases. However, it was still relatively unknown how sleep loss could influence our own hidden biases. This is not just an interesting question but an important one too when you consider that implicit biases can negatively guide our behaviour outside of our awareness.

Therefore, in a paper published last month a team from Harvard University explored this question and wanted to understand whether chronic sleep deprivation could lead to an ‘unmasking’ of negative implicit biases. More specifically, they asked: Are we more likely to express an implicit negative bias towards Muslim Arab names when we are sleep deprived?

To test this question, seventeen participants were invited into the laboratory for 25 days and it was under these strictly controlled walls that participants’ sleep was monitored. During this period, invited participants spent five days on 4 hours sleep and two days on 8 hours. This continued for a total of three weeks. The same participants, were invited back 2 months later to spend another three weeks in the laboratory but this time they could sleep for 8 hours every night. This meant that each participant served as their own control for the study. On the 21st day participants were given the implicit association test (IAT) for Muslim-Arab names and the scores during the well-rested and sleep-deprivation conditions were compared. The researchers predicted that during sleep deprivation participants would show an increased negative implicit bias towards Muslim-Arab names (i.e. they would be less able to mask their biases).

So, what did they find?

Well when participants were well-rested they did not show a negative implicit bias towards Muslim-Arab names. This is good and somewhat encouraging. However, when they were sleep deprived the same participants did show significant evidence of a negative implicit bias. That is, they more readily associated Muslim-Arab names with “bad” rather than “good”. This suggests that sleep deprivation may make us more likely to express our implicit biases.

Well before we get carried away this task is not a perfect way to assess unconscious biases and simply because our perceptions are unconsciously altered does not mean our behaviour is too. It’s also important to note that this group of participants did not have an implicit negative bias normally (e.g. when well-rested). Yet, it was possible to see that a moderate bias was found following three weeks of substantial sleep deprivation. On that note, it would be very interesting to see if in groups who already have an implicit bias show the same increase in bias following sleep deprivation and whether good sleep could reduce the negative implicit bias shown.

However, it does suggest that sleep deprivation in situations where workers have to act quickly and intuitively may bias our perceptions in a negative, and potentially fatal, way. This is particularly relevant for police officers, military personnel, and individuals working in airport security who may work long shifts and who may need to make snap judgements. We should be careful before anyone shouts from the rooftops “being sleepy makes you more racist”. This task is looking at implicit biases and the IAT do not represent explicit biases. In most instances we have the time, and resources, to make a balanced judgement. Nonetheless this research showed that a lack of sleep can negatively influence our own unconscious biases towards others. As for outright racism? A lack of sleep won’t suddenly make you racist – sorry Nige.

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References:

Alkozei, A., Killgore, W. D., Smith, R., Dailey, N. S., Bajaj, S., & Haack, M. (2017). Chronic Sleep Restriction Increases Negative Implicit Attitudes Toward Arab Muslims. Scientific Reports7.

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Filed under Politics, Psychology, Racism, Sleep Science

Have you considered sleep with that? How global warming may stop us getting a good night’s sleep

Insomnia and Heat

When we think about increasing global temperatures we tend to think melting ice caps, flooding, and conspiracy theorists who believe scientists (or the Chinese) make this stuff up to exert some unknown power and influence. However, the temperature at night has a direct influence on the quality of our sleep too. So, I’m back to talking about sleep again (the sigh of relief from my adoring crowd is audible – thank you). A recent paper, published in Science, has shown that global warming will not just have an effect on political alliances but also on our sleep. Trump, take note.

The premise of the recent paper, by Dr Nick Obradovich and colleagues, is a simple but profound one. As the summer months trundle on by (and yes, we get some occasional sunshine here in the UK too) you are probably acutely aware of the nightly sojourn to bed and futile attempts at sleep in the oppressive heat. Unless you have the advantage of a trusty fan or even a hint of a breeze outside you know you are going to toss, turn, and throw the covers around until you eventually nod off for a few fragmented hours. Temperature has an evident ability on our ability to get to sleep. This is shown clearly when we consider the changes in body temperature throughout a typical night. As we drift off our body temperature reduces and remains lowered during the sleep period until we wake up. At this point, it starts to rise again helping to improve alertness during the day. This pattern, or circadian rhythm, is no accident – it helps to send us off to sleep. This rise and fall is important and if we increase our temperature too much (e.g. lying in a particularly stuffy room) then we delay the time at which we drop off and are more likely to wake up during the night.

It is this quirk that a research group explored in relation to global warming. In light of what we know, will the increase in global temperature negatively influence our sleep? We can assess this by looking at unseasonably hot days during a month and correlate this with the reported number of nights of poor sleep in the population. This is exactly what Obradovich and colleagues did. They assessed the temperature changes from the average in a number of cities across the US and identified the sleep habits of hundreds of thousands of respondents to a large survey assessing health and disease. They controlled for potential confounders and found that as the temperature increased from the average, for any given month, that there was an increase in reports of nights with disturbed sleep. In fact, as the temperature rises then so does the number of disturbed nights of sleep. When the group compared low and high earners and young and old populations they found that those who were poorer and older tended to suffer more from the effects of temperatures spikes. Finally, as would be expected, they found that these effects were only significant when they looked at the summer months.

This highlighted largely what we already know: that temperature negatively impacts on sleep quality by interfering with the normal process of drifting to sleep. However, the interesting point comes from the next finding of their study. They identified the predicted increases in global temperature until the end of the century from NASA. They then plugged in these values from the first part of the study to identify the effect of increasing temperatures of the number of nights sleep loss until the end of the century. Somewhat worryingly, they found that over the next century the number of nights poor sleep increases in line with the increases in temperature in part due to global warming and climate change. This has implication for physical and mental health which has consistently been tied to the quality and duration of our sleep.

It is important to note that there are plenty of caveats to this study. For example, its indirect and correlational measure of sleep and temperature should raise some concerns about the validity of the findings. Furthermore, it’s important to note that sleep was assessed with a single self-report question, “During the past 30 days, for about how many days have you felt you did not get enough rest or sleep?”. As the authors suggest, further experimental data is needed to back up their claims.  However, the findings from this study do fall in line with what we already know about the effect of temperature on sleep. It is not a stretch to claim that global warming, ignoring other external factors, will have a negative impact on our sleep. There are of course ways to mitigate the negative effects of increasing global temperature but this study also accounted for that. The poorest and oldest stand to suffer most as they cannot afford to keep air conditioning running all night. Therefore, although this is one admittedly large-scale study there is still additional research which needs to further understand the true impact our warming climate will have on our sleep and subsequent health. For the time being, it raises an important reminder that the effects of global warming are far reaching and ignoring the clear evidence for its existent is nothing short of irresponsible and short-sighted. Again, take note Mr. President.

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References:

Obradovich, N., Migliorini, R., Mednick, S. C., & Fowler, J. H. (2017). Nighttime temperature and human sleep loss in a changing climate. Science Advances, 3(5), e1601555.

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The Human Microbiome: A Teeming Ecosystem Within Your Own Body

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Meet the neighbours: here’s Paul, Sandra, Jack, Lily, and so on and so on

“Why have you stopped speaking about sleep?”

“I can have other interests!”

“I don’t know man, you’ve changed. Why should I care about anything you have to say now?”

“…”

What is a microbiome? That’s a very good question. For a start, it’s not some artificial eco-project which is attempting to save the world or even, I’m sorry to disappoint you, some form of miniaturised food either. The microbiome refers to the different ecosystems of microbes which we have all over our body. These microbes use us as their home and in turn can benefit us, live mutually alongside us, or cause us problems. They form a complex and important addition to the multitude of cells which make up our own bodies and recent estimates suggest there are as many microbial cells as there are cells which make us up. One particularly well studied microbiome requires us to get to the bowels of every one of us. Quite literally. This ecosystem is the one we find in the human gut. This microbiome has also attracted a lot of interest because of its impact on the brain known as the gut-brain axis (more of this in the next article). In general, microbiome research is still in its infancy and everyone wants a piece of it. This is likely because it seems to play an important role in a number of different mental and physical functions and there is even talk of this ecosystem containing our ‘second genome’. So, what does this all really mean and why should we care?

The ecosystem of microbes (e.g. bacteria, fungi and viruses) which live alongside us help to break down food, protect us from invaders and produce nutrients necessary for our health. One good example of the benefits of the gut microbiome is evident in looking at babies and breast milk. There is a particular group of complex sugars known as human milk oligosaccharides (HMOs) which make up a considerable amount of breast milk. However, despite their prevalence in mother’s milk babies do not have the ability to break them down. This should make them rather useless to the baby and a waste of resources for the already energy-stretched mother. Indeed, this finding initially stumped scientists as breast milk has evolved to be the perfect nutrition for an infant – why should it contain something a baby cannot digest? However, it seems that a specific HMO, B. infantis, in the infant’s gut is the intended target of this sugar instead. B. infantis can break down the complex sugar and in turn flourish in its presence. Why is this a good thing? Well it is hypothesised that the healthy colony of B. infantis force out more harmful bacteria from making their home in the infant and act as decoys for potential pathogens keen on harming the bleary eyed newborn. Moreover, this rather nifty bacterium promotes gut health and has anti-inflammatory properties. The mother’s breast milk helps ensure this positive bacterium survives and in turn the bacterium ensures the baby is more likely to survive.

How about in adulthood though? What are some of the functions of our microbiomes scattered around our body? Well the ‘second genome’ seems to play an important role in our behaviour and health. For example, in a series of experiments which looked at the effects of transferring human bacteria from obese and lean twins to germ-free mice. The researchers found that when the mice were given the bacteria from the lean twin they stayed the same weight; however, when the bacteria were from an obese twin they gained weight. This is despite the mice all being given the same amount of food to eat. Furthermore, it seems that lean mice which live together with obese mice have the capacity to transfer their ‘healthy’ microbiome. Yet, the obese mice could not transfer their bacteria to the lean mice. This, it is argued, was because the obese mice have a lower diversity of bacteria within their gut microbiome and this leaves space for new species (found in the lean mice) to colonise and flourish. The bacteria of the lean mice tend to win in these situations. However, the positive effect of the transfer of bacteria on the obese mice is not universal. It requires that the obese mice have the right diet in the first place. If the obese mice were fed a westernised diet high in junk food and saturated fats then the positive impact of the bacteria from lean mice was non-existent. The positive effect was seen only if the obese mice were eating a healthier diet from the start. It could be speculated that this is because the high-fat diet does not promote the survival of the bacteria found in the lean mice’s gut. This opens up the exciting possibility that our gut bacteria are having an important role in our weight and health. It is possible that a particular diet might be able to promote the colonisation of new species of bacteria within our microbiome and, in turn, help promote weight-loss.

The human microbiome has also been linked to illnesses characterised by disruption of the normal functioning of the immune system. It has been argued that autoimmune conditions such as crohn’s disease and ulcerative colitis may be linked to a failure of the gut microbiome to develop appropriately during childhood. It’s claimed that this is because of the increased use of antibiotics and high-fat, low-fibre, diets which characterise the western world. The presence of these environmental factors reduces the diversity of the gut microbiome and interferes with the normal process of teaching the immune system how to function. In addition, certain species of bacteria appear to have anti-inflammatory effects which researchers are trying to capitalise on as treatment possibilities for inflammatory bowel diseases (IBD).

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Understanding the gut microbiome holds promise for the treatment of IBD.

So, it looks like the gut microbiome can have profound effects on our health. With this in mind, can we change our gut bacteria? Well, there are a lot of potential problems with this. Our gut microbiome seems to be influenced by the microbes which our mother and father impart upon us at birth (particularly from our mother). However, during infancy we go through a fluctuating development of our microbiota and the constituent microbes change considerably as we progress to adulthood. This is why some researchers believe that it is during early childhood that any attempts to modify the microbiome will be most effective. It is during this period of flux for our plucky neighbours that attempts to modify the microbiome are likely to be most effective and long-lasting. If there is a link between our gut microbiome and autoimmune disorders it is likely that this stage of our development is critical to reduce the risk of IBD. However, during adulthood there is more stability of our microbiome. The gut microbiome appears resilient to change following diet in the short-term but it is possible that long-term dietary changes might create a more favourable environment for new microbial species. For example, when the initial gut bacteria colonise an area they change the environment so it is more beneficial to their survival compared to other species. Therefore, although there is an obvious benefit to improving our diet, whether this boosts our microbiome is not quite known yet.

The human microbiome is not confined to our guts but our mouths, throats, noses, genitals and skin, to name but a few, are also examples of microbiota within the human body. For example, we contain our own signature of gut bacteria on our hands although there is considerable variation between individuals and even between our own two hands. It is not known exactly what is responsible for this variation but a mixture of genetic and environmental (e.g. hand-washing, climate, sex, etc.) factors seem to be important. It is also possible to shift the microbial constitution of someone else’s hand through direct contact – a handshake. How long the changes remain, however, is not clear and it is likely that the ecosystem carved out by your own skin microbiome favours the microbes usually residing on and in your skin. This is perhaps something to keep in mind when meeting your hero and desperately trying to shake their hand. It may be that greatness can rub off on others through a firm handshake. Also, in a similar manner to the gut microbiome, the composition of microbes on the skin has also been linked to health and disease. A good example of this is psoriasis which involves the development of plaques on the skin of those affected. In a similar manner to the gut microbiome, it is likely that a wider diversity of the skin microbiome has anti-inflammatory properties which are protective against auto-immune disorders such as psoriasis.

So, does this mean that all of us need to alter our eating habits to ensure that our gut bacteria are working at their best? Probably not for the time being. This is the nature of any research in its infancy and beware of any book or news article which claims that changing your microbiome through diet will improve your health. Despite all the excitement surrounding the microbiome at the moment we need to be aware of the limitations of research which seems to be ‘in vogue’. There is plenty of high-quality research which is being carried out in this area but much of this research is conducted in mice and the human research is largely correlational. It’s currently difficult to infer cause and effect – does poor health causes changes in our microbiome or vice-versa or, more likely, is it a mixture of the two? We need to be aware of how little we really know about the microbiome at this current moment. For example, we don’t know what a healthy microbiome looks like. Is there one individual ‘optimal’ combination of microbes to strive for or is it that a greater diversity, in general, is best? There seems to be some evidence of ‘types’ of stable microbiomes in adults but this work is still in development. There is also some evidence which links a healthier, fibre-rich, diet to a greater diversity of microbes within the gut microbiome but it is unclear what impact this has on health and behaviour. Currently, the Human Microbiome Project is trying to understand what the normal limits of the microbial ecosystems look like and how they might be implicated in health and disease. Although they started in 2008 and have received considerable funding there is still a long way to go before we see these findings directly influencing health. There is plenty of excitement about the microbiome but it is still early days for this field. For now, the human microbiome holds a plethora of secrets yet to be unlocked about the teeming, fluctuating, and enigmatic organisms we share our body with.

Image Credits:

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Body Image

References / Recommended Reading:

http://www.nature.com/news/bacteria-from-lean-cage-mates-help-mice-stay-slim-1.13693#/ref-link-1

https://www.nature.com/articles/srep32484

http://www.nytimes.com/2013/05/19/magazine/say-hello-to-the-100-trillion-bacteria-that-make-up-your-microbiome.html

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3535073/

https://www.nature.com/cti/journal/v5/n4/full/cti201612a.html

http://www.nature.com/news/scientists-bust-myth-that-our-bodies-have-more-bacteria-than-human-cells-1.19136

http://hmpdacc.org/ (Human Microbiome Project Website)

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3577372/

https://www.ncbi.nlm.nih.gov/pubmed/20668239/

http://www.newyorker.com/tech/elements/breast-feeding-the-microbiome (An extract from the amazing Ed Yong’s book, ‘I contain multitudes’)

http://www.radiolab.org/story/funky-hand-jive/ (A hilarious and brilliant podcast on this topic)

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How can escaping into virtual reality improve healthcare?

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You slowly creep towards the door while being acutely aware that the slightest sound will get you caught. As you reach for the handle and steadily open the large wooden door you hear a slight creak. Suddenly, the expansive and exposed wall to your right explodes in a flurry of shrapnel, wallpaper and dust. A figure starts to emerge from the wound in the wall and stares directly at you with a terrifying smile. You’ve been found out…

Virtual reality isn’t always quite so terrifying but the above example reminds us that the virtual world has the capacity to make us believe what is thrust directly in front of us. The fear is real and the experience is one which mimics the experience of navigating a trap ridden residence. Besides terrifying us and fuelling visions of humanity being locked in a virtual world to escape the real one, what is the future of virtual reality? Well, one emerging area appears to be concerned with improving mental health.

Use of virtual reality to treat mental health difficulties

Psychosis, a cardinal symptom of schizophrenia, is the presence of delusions and hallucinations which can cause considerable distress. Delusions can take many forms and the nature of these seem to be tied to the diagnosis present (e.g. bipolar disorder, depression or schizophrenia). One delusion common to those diagnosed with schizophrenia is paranoia which can, understandably, cause significant distress and impairment in an individual’s life. However, what if we could challenge the paranoid thoughts of those experiencing psychosis and illustrate their unfounded nature? A real-world setting is likely to be too anxiety-provoking for obvious reasons but what if we could recreate paranoia-inducing environments in the relative safety of virtual reality?

This is exactly what a group at the University of Oxford led by Professor Daniel Freeman has explored in their study for the British Journal of Psychiatry last year. They exposed individuals with persecutory delusions (e.g. paranoid thoughts) to one of two mock real-life setting through virtual reality and asked them to do one of two things. One group was simply exposed to the virtual environment and asked to simply experience the situation. The effect of this on their their paranoia was assessed. The second group, by contrast, was asked to drop their guard, stop using their safety behaviours, and actively put their paranoid thoughts to the test (e.g. Do people in this environment see me as an easy target and do they actually do things to belittle me?). This second condition was known as the cognitive therapy group as they were encouraged to actively re-evaluate their delusions in the safe confines of the virtual environment.

There were 30 participants tested and they were randomised to either an exposure or cognitive therapy condition. They were tested in a real-life setting initially, then gradually introduced to the virtual reality environment, and then finally tested in the real life setting once again. At each point participants were tested before and after their immersion to either real-life or virtual reality on a scale assessing the conviction and distress of paranoid thoughts. As a test of ‘credibility’ the participants were also asked whether they believed the virtual reality setting would help them overcome their paranoid thoughts. Participants were tested in one of two different virtual reality settings. The first setting was a typical one for any Londoner: a tube journey. The second was a lift which the participant walked into and could inspect the other passengers.

So, what did they find? They found that there was a significant and large reduction in conviction and distress of delusions following the cognitive therapy group’s immersion into the virtual environments. Interestingly, these findings also carried over to the real-world setting. On average, they found a reduction in scores of around 20% for the cognitive therapy vs the exposure virtual reality condition. This suggested that getting individuals with paranoid delusions to test out their threat beliefs in a safe environment had the impact of reducing their paranoia. This should be considered in light of the difficulty to achieve this in a real life setting due to considerable anxiety and stress. This suggests that virtual reality is a simple and effective way to combat threat beliefs in paranoia.

However, this was only completed over a single day and the long-term impacts of using virtual reality is this way are currently unknown. Is there a dose-dependent effect of VR on threat beliefs? How long do the therapeutic gains last for? Are there individuals for whom this works better or worse? Are there any unintended side effects of using VR for multiple sessions in a patient population? And many other questions which remain to be answered. Psychosis is not the only field where virtual reality has started to prove its worth in treatment and research but anxiety, depression and eating disorders are also highlighted in the recent review by Professor Freeman earlier this year.

It should be noted that virtual reality is by no means only being realised within mental health but it is starting to be used extensively within physical healthcare too. VR provides an optimal way to train new surgeons, doctors, and nurses in medical procedures. This is what current research is exploring and virtual reality is only one avenue. Augmented reality is becoming more common and apps such as VR in the OR allow us to witness surgical procedures in an interactive manner from the comfort of your own home.

Basic Science and Mechanisms Research

So, there appears to be promise for using virtual reality as a way to deliver therapy but what about research more basic, mechanistic, research (e.g. what causes paranoid thinking in the first place)? Surely if we can create a convincing setting then we could start to study how threat beliefs are generated, in the case of psychosis, or understand what might reduce of exacerbate mental health difficulties in general. In an earlier study conducted in 2003, Prof. Freeman showed that paranoid thoughts could be seen in a virtual reality setting with healthy individuals. In their early foray into the use of VR they found that a small number of participants in their sample attributed hostility towards the avatars present in the environment. The researchers argued that this showed that VR could be used to study paranoia and provide a more realistic environment to test predictors of paranoia in a social setting.

Finally, because we can treat these virtual realities as realistic and convincing, they provide a great landscape in which to explore situations which might prove difficult for those at risk for certain mental illnesses. This allows researchers to test out hypotheses without unnecessarily exposing participants to a threatening situation, and with the ease of removing the headset instantly if the situation becomes distressing. For example, it would be possible to further probe the effect of sleep on mood and how this might contribute to mental health difficulties through the use of virtual reality. Now, as with any science, the worth of the study is not dependent on how flashy the toys are which are used but the strength of the research question and design. Although VR may strike some as flashy, it is useful in that it provides a way to recreate reality but in the controlled and safe confines of the lab. VR may currently be synonymous with jump scares and large price tags it is also being used to improve the health of the public. The widespread use of VR across healthcare settings is still a while off. For now, we shall just have to be content with scaring ourselves senseless with Resident Evil and other horror games.

References

Freeman, D., Bradley, J., Antley, A., Bourke, E., DeWeever, N., Evans, N., … & Slater, M. (2016). Virtual reality in the treatment of persecutory delusions: randomised controlled experimental study testing how to reduce delusional conviction. The British Journal of Psychiatry, 209 (1), 62-67.

Freeman, D., Reeve, S., Robinson, A., Ehlers, A., Clark, D., Spanlang, B., & Slater, M. (2017). Virtual reality in the assessment, understanding, and treatment of mental health disorders. Psychological Medicine, 1-8.

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Virtual Reality (Header)

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Filed under Psychology, Schizophrenia, Work and Society

Can we modify specific stages of sleep to improve our memory?

Sleeping Kitten

Our memory is far from perfect. You have probably gone into another room and completely forgot what you went in there for. You stare into space and hope it will come back to you. Was it to pick up keys, tidy something or speak to someone? Nope, it just doesn’t come and you walk back slightly dazed and annoyed at your ailing memory. This is just a small example of the times our memory fail us during our day-to-day lives. However, what if we could improve our memory while we sleep?

Sleep is important. I’d like to think that I’ve impressed on you all by now. It protects us from certain metabolic disorders, keeps us alert to our surroundings and maintains our mental health and overall mood. There is some evidence to suggest it helps the brain’s natural waste disposal systems but that’s still in its very early days (despite some bold claims in the mainstream media). All of these areas have garnered substantial interest from scientists but memory is the one we’ll be focusing on. Typically, studies show that our ability to lay down new memories improves after a simple nap or a good night’s sleep. This, of course, isn’t always practical but it provides us some insight into what is happening in the brain when we drift off. It also should remind anyone revising for exams that sacrificing sleep is a false economy – unless of course you need to cram. Sleep can only help you so far there.

The link between sleep and memory raises an interesting question: what is it about this period of seeming inactivity that may help improve our memory? Sleep is far from a unitary construct and if we could identify the specific stage or stages which are crucial for memory then perhaps we could capitalise on this. We go through different stages of sleep, broadly, broken down into Non-REM and REM, and these are made up of different brain cell oscillations (see picture below) within the brain. Through probing the different stages, we can start to understand which are more important for memory. So, what are some of the candidates for sleep’s role in memory? The main contenders are sleep spindles and slow wave sleep (although REM has also been claimed to play a role in memory too).

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Stages of sleep recorded from EEG

Sleep spindles are characteristic of sleep stage 2 and are brief bursts of activity seen when using a brain imaging device known as electroencephalography (EEG). Imagine one of the funny caps with electrodes protruding out as you probably have a good idea of the typically EEG setup. Sleep spindles have been claimed to be important for memory consolidation and form a key part of one of the main hypotheses for how sleep might boost our memory. More specifically, it is argued that sleep spindles may facilitate the movement of memories from temporary consolidation in a part of the brain known as the hippocampus to the rest of the brain. Interestingly, sleep spindle activity correlates with performance on memory recall following sleep, and spindles show an increase following learning. The activity location of the spindles seems to be associated with the location of brain activity engaged during intensive learning of a specific function. As a result, some have suggested that sleep spindle activity may be used as a marker for learning potential (Fogel & Smith, 2011). However, the reality is likely more complex than this. Nonetheless, it does point towards spindles as a potential marker of memory consolidation during sleep.

In addition, slow wave activity (SWA) has also been shown to be important for memory. These are the slow (1Hz) oscillations characteristic of deep sleep. It has been this stage of sleep which has primarily been targeted to improve memory in previous studies. More recently, slow wave activity and sleep spindles have been successfully modified through the use of electrical stimulation of the scalp, drugs, playing sounds throughout the night (specifically timed and not so loud as to wake the participants), and even by presenting odours present at the time words were initially memorised.  These manipulations have been shown to improve memory and it seems it does this by increasing the amount of slow wave activity and sleep spindles. This work, although still in its infancy, suggests that it possible to stimulate specific features of sleep and, in turn, improve a vital cognitive function. It is at this point that a recent study in the aptly titled journal ‘Sleep’ comes in.

A group at the University of Helsinki in March this year (https://www.ncbi.nlm.nih.gov/pubmed/28364428) built on these previous findings by trying to identify a way to automate this process of stimulating slow wave activity. The success of this aim would increase the ease of introducing this technique into a home-setting and allow for the modification of sleep coveniently. The group decided to try to find a way to target sound stimuli to slow waves automatically in the hope of improving specific types of memory without affecting the sleep quality or mood of the participant. This is crucial as it is little use improving memory and modifying sleep if it causes other problems at the same time.

How did the researchers attempt to automate this process? They recorded electrical activity from the brain during sleep and were able to identify slow wave activity automatically by looking out for a specific frequency band (i.e. how often a waveform occurs over a set period of time). Whenever slow wave activity, indicative of deep sleep, was identified in the sleeping participant, a computer program sent a message to another device which played a brief sound. This meant that the sound was played just after a period of slow wave activity. Following this, there was a break of least 2 seconds between each sound being played. The loudness of the noise was changed automatically in response to cues from the participant. For example, if it seemed that the participant was waking up then the sound was lowered.

With the system in place, a total of 15 participants were invited into the lab for three days, each day separated by a week, to test out the automated approach to increase slow wave activity. The first day involved a familiarisation night so that the participants could get used to sleeping in the lab and with the equipment setup. During day two, one half of the participants heard the automated sounds and the other half did not. This was then switched for the third and final day. This allowed the researchers to compare performance on memory tasks when the sounds were not played and when they were not.

So, what did they find? Firstly, and importantly, they showed that their automated enhancement of slow wave activity was successful and viable. It managed to increase slow wave activity and sleep spindles. Moreover, the automated sounds were also found to increase memory overnight. They showed that word-pairs could be enhanced by playing a relatively quiet sound during slow wave activity. The interesting outcome of this study is that the possibility of having an automated system which people could use at home to boost memory. For populations who have poor memory this could hold promise as a therapeutic tool. It is a while off anything like this being available but it tells us something about how sleep contributes to memory and the potential ways we can exploit this in the future.

Although it is still unclear how exactly sleep is linked to memory, it is research like this which is starting to uncover that our brains are anything but quiet during sleep. Although there is likely to be no device which will improve your memory overnight on the market any time soon, scientists are working on the concepts necessary for this to become a reality. For now, perhaps you could try writing down what you’re about to do before walking into a new room?

ResearchBlogging.org Leminen MM, Virkkala J, Saure E, Paajanen T, Zee PC, Santostasi G, Hublin C, Müller K, Porkka-Heiskanen T, Huotilainen M, & Paunio T (2017). Enhanced Memory Consolidation Via Automatic Sound Stimulation During Non-REM Sleep. Sleep, 40 (3) PMID: 28364428

Additional References

Fogel, S. M., & Smith, C. T. (2011). The function of the sleep spindle: a physiological index of intelligence and a mechanism for sleep-dependent memory consolidation. Neuroscience & Biobehavioral Reviews, 35(5), 1154-1165.

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Sleeping Cat (Header)

Sleep Stages (Body Text)

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Trauma, Tetris and Memory: A Cheap Way to Reduce the Impact of Intrusive Memories

Body Image

What if I was to tell you that playing video games can be good for you? That despite derision and their use in political point scoring, games such as Tetris and Candy Crush could one day be used to help people deal with traumatic events in their lives? You might be initially sceptical but there is growing evidence to support this. Although not a new idea, Tetris has been shown to be useful in reducing the uncontrollable intrusions associated with a traumatic experience.

So, how can we use a video game such as Tetris to interfere with traumatic memories? Well, in much the same way that you would interfere with any memory. As you create a new memory and have converted all the constituent parts into a form which the brain can understand, it goes through a period of consolidation. That is where the memory is stored within your brain so you are able to recall it at a later point. Now if we interfere with the memory during this period of consolidation it is less likely that we will recall said memory. For example, if we can provide some competition for the neural real estate the original memory is vying for then we can weaken the strength of that original memory. It seems to be important that the type of memory is relatively specific and needs to match the original memory’s modality (e.g. a visual-spatial task needs another visual-spatial task to compete with it effectively). This is essentially where Tetris comes in. The authors argued that if both the trauma memory and Tetris rely on the same visual-spatial resources then you can reduce the intrusiveness of the initial trauma memory.

This is exactly what Emily Holmes at the University of Oxford and her collaborators found in studies conducted over the past eight years. If you ask a participant to play Tetris 30 minutes after a lab-controlled trauma induction you can reduce the impact of the traumatic memory compared to a control condition. These early studies showed that, at least in the lab, you could interfere with traumatic memories in a therapeutic way by reducing their intrusive nature. Although they were not carried out in a naturalistic setting they provided evidence that the proposed mechanism existed and could be manipulated. It is also key to keep in mind that this study showed that playing Tetris reduced specifically the intrusiveness of the traumatic memories and not the deliberate recall memory for the event. As the uncontrollable nature of the traumatic memory is a source of considerable distress in PTSD it is important that any intervention can have a targeted effect. What about evidence for the use of Tetris to deal with naturally occurring trauma outside of the lab? This is where their latest study, published in Molecular Psychiatry, last week comes into play (it’s open access so you can read the full article yourself here).

In a small-scale naturalistic study in Oxford, Emily Holmes, and colleagues at the Karolinska Institute in Sweden, examined individuals in A&E who had recently (within 6 hours) experienced a motor accident as a driver, passenger or pedestrian.  They randomised 71 eligible participants to either an intervention or control condition to test the real-life application of their previous findings. In the intervention condition, participants were asked to recall the traumatic event initially and to then spend at least 10 minutes (maximum 20 minutes) playing Tetris. By contrast, the control condition asked participants to write down all the activities they carried out during their time in A&E (e.g. completing a crossword, speaking to a friend, etc.). Participants were assessed at one week and one month following either the control or intervention task. During the initial week participants were required to complete a daily diary of the number of intrusive memories they experienced which were related to the trauma (e.g. motor accident). The participants were instructed not to report “memories recalled deliberately or general verbal thoughts”. The number of intrusions provided a primary way to assess the success of the use of the intervention (memory cue and Tetris).

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So, what did the researchers find? Primarily, they showed that the use of Tetris and memory recall was an effective intervention. The number of intrusions was significantly reduced in the intervention group after one week (9 intrusions on average) compared to the control condition (23 intrusions on average). Furthermore, they also found that the intervention group also reported significantly less distress after one week. However, this reduction in distress did not remain when participants were followed up after one month. To supplement this data, the authors also asked the participants about their subjective experience of using the intervention. Their reports were positive and it was apparent that they appreciated the distraction from the accident which playing Tetris offered. One participant highlighted this clearly with, “it certainly took my mind off of it at a time when I probably would have sat brooding and feeling very sorry for myself…”. Another participant, who had not played Tetris before, was keen to keep playing it following the allotted 20 minutes. The intervention thus proved to be both feasible and acceptable.

Together, these findings support the usefulness and viability of using Tetris to combat intrusive traumatic memories in a real-life setting. The reduction in the number of intrusions following a natural traumatic event (e.g. motor accident) supports the intervention and suggests it could be a low-cost, easy to administer, therapy. As the authors highlight in the paper, waiting times in A&E can be as long as 4 hours and this would be an ideal time to target individuals who have experienced a traumatic accident. As a well-tolerated, and simple, intervention it seems ideal. However, this study is simply the beginning of translating Tetris, or similar aproaches, into the realms of clinical practice. Although this trial did not show an effect on distress at a one month follow-up, a larger trial may be better suited to pick out subtle effects for longer periods of time. Furthermore, additional doses of the intervention may also prove effective as a ‘booster’ to the initial dose. As any good piece of research, this trial raises more questions and exciting avenues for further study.

Alongside the compelling results, why should we be so excited about this research? It provides clear evidence that marrying cognitive neuroscience and clinical practice are vital for progress in both fields. It is still early days for this collaborative approach but hopefully this soon blossoms into a powerful and fruitful relationship. Basic science studies can be blamed for being too distant from the disorders and clinical fields they are trying to unpick and affect. However, with a greater understanding of the mechanisms at work behind mental distress we can develop novel therapies, like the use of Tetris, to target them and help real people. Personally, that is one of the amazing things about research and one of the reasons why I fell in love with science in the first place. More work is needed to validate these findings but, at least for the time being, they provide you with a great retort to anyone who claims video games are good for nothing. To quote Emily Holmes’ original Tetris paper in 2009, “…clearly not all computer games are bad for you.”

ResearchBlogging.org

Iyadurai, L., Blackwell, S., Meiser-Stedman, R., Watson, P., Bonsall, M., Geddes, J., Nobre, A., & Holmes, E. (2017). Preventing intrusive memories after trauma via a brief intervention involving Tetris computer game play in the emergency department: a proof-of-concept randomized controlled trial Molecular Psychiatry DOI: 10.1038/mp.2017.23

Additional 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.
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Tetris (Header)

Tetris Building (Body)

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Sleep’s Positive Impact on Traumatic Memories

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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.

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Bad Memory (Header)

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