Sleep deprivation affects how we interpret emotional cues

yawning boyby Dennis Rosen, MD – Associate Medical Director of Children’s Sleep Laboratory

A lot of research has been done about how not getting enough sleep affect someone’s ability to function. Whether this is shown in how someone performs on tests measuring cognitive abilities, behavior or even behind the wheel of a driving simulator (and responding worse than some whose blood alcohol levels exceed the legal limit), the results all support the premise that getting enough sleep is crucial if someone wants to achieve their full potential.

A new study has found that sleep deprivation interferes with people’s ability to distinguish between the facial expressions of others, specifically to determine whether they are happy or angry.

In this study, 20 people were deprived of sleep for 30 hours and then asked to look at photographs of faces, each displaying a different emotional state – happy, sad and angry – at various levels of intensity. Then they were allowed to sleep and retested 24 hours later. The responses from both days were compared, as well as to those of another group of 17 people who served as controls, undergoing the same testing two days in a row without sleep deprivation.

The researchers found that there was a significant weakening in the ability of those who had been tested while sleep deprived to distinguish between angry and happy facial expressions in the moderate intensity range. This difference disappeared after recovery sleep and was greater in women than in men.

What is the significance of these findings? First, they expose yet another area in which getting enough sleep is critical for normal daily function. They may also explain why overtired children become especially grumpy and moody and are just generally less pleasant to be around the more sleep deprived they are. Some of this may result from a decrease in the ability to accurately interpret messages and signals being given by family members, resulting in exaggerated or even inappropriate responses.

One question that arises which I find especially intriguing is what this may mean for children (and adults) with autism, who by definition have difficulties interpreting social cues. It is known that the prevalence of sleep disorders in children with autism is much higher than in the general population. So, one could ask whether the sleep disturbances seen are solely a consequence of the autism, or whether they not only coexist, but also play a role in strengthening some of autistic features. If that is the case, perhaps we should be more aggressive in treating sleep disorders in this population.

While the numbers in this study were small, it certainly raises many important questions, which will no doubt continue to be looked at going forward.

Read more of what Rosen has to say on children and their sleep on his blog, Sleeping Angels.

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