We’ve already covered sleepwalking in some detail and identified how complex behaviours can be initiated during a period of seeming unconsciousness. These behaviours can take a wide range of different forms. For example, reports of sleep-texting are becoming more common, which highlights how changes in our daily routines lead to changes in the type of sleepwalking behaviours. Next on our list is to shed some light on why we might talk in our sleep too.
“Jack…? Are you awake? What’re you talking about?”
“Ignore him, he’s speaking in devil-speak again. He does that. Admittedly, it’d be less freaky if he didn’t have his eyes open at the same time too…”
Apparently I didn’t form full sentences in my sleep during my spate of sleep-related weirdness as a child, but sounds resembling more than mumbling could be identified by friends whenever I stopped over. Alongside the heart-attack-inducing brush with sleepwalking which my parents were forced to endure, I also ‘entertained’ my friends by talking in my sleep – or engaging in somniloquy, as it’s also known.
Sleep talking is an experience which many of us will come across at some point in our lives. It is a relatively common phenomenon and can be found predominantly during childhood, but also as a rarer occurrence within adulthood. However, the prevalence in adulthood varies considerably. It is one of the most frequent parasomnias (disorders of sleep which involve some form of unusual or unwanted behaviour during sleep) found between the ages of 3-13 years old (Laberge et al., 2000), and it appears slightly more often in boys of this age than girls.
Sleep talking is associated with sleepwalking, and one may predict the subsequent occurrence of the other (Ohayon et al., 1999). This is not surprising, as many parasomnias are found together, or increase the likelihood of someone experiencing another. The main concern during adulthood is the potential embarrassment which might come alongside the sometimes nonsensical muttering, and potentially the content which is said. However, it is generally accepted that sleep talking, although impressively coherent at times, is not necessarily truthful or meaningful. For example, it is not admissible in court and the individual will have no memory of what they said or even that they were talking in their sleep. This is part of the reason why it is so tricky to work out the prevalence of sleep talking in adults.
When does sleep talking occur? Well, like many other parasomnias, it appears that it can occur across the sleep-cycle. The quality and coherence of the speech during sleep may differ as an individual goes from light, deep and finally to REM sleep. The exact link between sleep stage and speech is uncertain, but it has been argued that REM sleep is associated with more coherent and daytime-like conversations. There is also evidence to suggest that it runs in families, although environmental factors may make it more likely.
What causes sleep-talking and should we be concerned? For the majority of us, no. It is a harmless, if amusing, occurrence and may only occur in episodes which can be traced to an environmental cause. For example, it can be brought on by a number of factors such as sleep deprivation, stress, alcohol and fever. However, there may be problems associated with the effect of sleep talking on a bed-partner. This may produce problems in the person who shares the bed with the sleep-talker, who may find themselves being kept up and experiencing insomnia-like symptoms. Some studies have highlighted a link between adult sleep talking and some psychiatric illnesses, but it is far from conclusive what the nature of this link is. For the most part, sleep talking is a harmless, if slightly embarrassing, behaviour.
Sleep talking can also occur in the context of other illnesses such as night terror, nightmares, sleep apnea and REM behaviour disorder (RBD).
Other areas in which sleep talking may occur:
One way in which we can explore sleep-talking is in the presence of noted disorders during sleep. One example, where sleep-talking and movement are found, is night terrors. These are a form of sleep disturbance which occurs mainly during childhood. They are characterised by thrashing, panicked-like behaviour and screaming which occurs for several minutes. The child has no memory of this, and it can be considered a disorder of arousal like sleepwalking. In a similar manner, they can be exacerbated by anxiety, poor sleep schedules and behaviours which disrupt sleep (e.g. needing to go the toilet). Although this is not your archetypal description of sleep-talking, it is an example of how the boundaries between sleep and wake are blurred.
REM Behaviour Disorder
This is another disorder of arousal and, like night terrors, also involves elaborate movement and speech during a period of sleep. This occurs more commonly during middle age and is associated with more insidious origins such as the onset of Parkinson’s disease. At a basic level, RBD can be considered the acting of dreams, and the behaviours shown typically match with dreams had by the individual with RBD. However, dream ‘enactment’ can occur alongside many other sleep disorders, and the diagnosis of the disorder needs to be confirmed with the use of methods to study brain and muscle activity during sleep.
It’s important to note for that all the knowledge which we have amassed on the topic of sleep, we are still uncertain about so many different aspects of it. Sleep-talking fits into that snugly, and although I can provide indirect forms of evidence about what causes sleep-talking, it is very much left to scientists to further explore disorders of arousal and explore their causes in more detail.
Header Image: Sleep Troubles