Sleep and Reading Social Cues: A Link Never Tested in Children

What the research found

School-aged children allowed roughly thirty-five minutes more sleep than their peers performed better on a continuous performance test, a long and monotonous measure of sustained attention, and the difference was statistically reliable. The experiment was run by Avi Sadeh, Reut Gruber and Amiram Raviv and published in Child Development in 2003. Children were randomly assigned to extend or restrict their nights, and their sleep was recorded with actigraphy, a wrist-worn monitor that infers sleep from movement rather than from anyone’s memory of how the night went.

Comparable results have accumulated since. Six nights of moderate sleep restriction, again tracked by actigraphy, degraded performance on a sustained attention task in typically developing children and in children with ADHD alike, in work Gruber published in Sleep in 2011. Four nights of a bedtime one hour later than usual was enough to worsen children’s working memory in a 2013 experiment by Jennifer Vriend and colleagues.

Theory of mind is the ability to work out what is going on inside another person: what they believe, what they intend, what they want, what they feel. A child uses it to tell a joke from an insult, to notice that a friend has been quietly excluded, to grasp that someone acting confidently may not feel it. The first version of it consolidates around age four, and more demanding forms develop through the school years.

Writing in the journal Medical Sciences in 2017, Rackeb Tesfaye and Reut Gruber of McGill University set those two bodies of work beside each other. Their argument runs through executive function. The abilities that sleep loss reliably degrades, holding back a first response and keeping several pieces of information in play at once, are among the abilities theory of mind draws on. Emotional processing supplies a second route: sleep-deprived people show heightened amygdala response to unpleasant images and weaker connectivity between the amygdala and the prefrontal regions that damp such responses down, and the review reports a study in which more frequent night awakenings and lower sleep efficiency predicted worse performance at identifying simple emotions on faces in school-aged children.

Every strand in that argument is borrowed. Tesfaye and Gruber propose the link and state plainly that the relationship between sleep and theory of mind has not been studied. Their paper is a narrative review with no stated search protocol, and it reports no correlation, no effect size and no sample of its own. It is an argument for running an experiment that nobody has yet run.

What it means for you and your child

The situation the proposal speaks to is small and familiar. A child sleeps badly on Tuesday; on Wednesday at break a friend says something ambiguous, the child hears an insult in it, and the rest of the afternoon goes sideways. On the executive account, the fatigue that surfaces as a blurted answer in class would also thin the resources needed to hold two readings of a remark in mind long enough to choose between them.

What that Wednesday costs divides into a measured step and a proposed one. A short night degrades attention across a long dull task and weakens the holding of several things in mind, and those effects have been produced experimentally in school-aged children. Whether those same resources are what a child draws on to settle an ambiguous remark at break, against a quicker and less generous reading, is the step Tesfaye and Gruber take on argument alone.

No one has watched a child’s sleep and that child’s social reasoning together, which leaves the afternoon a hypothesis about where to look.

The prevalence figures and the experimental results were produced by different instruments. The review’s estimate that between 50 and 80 percent of children with ADHD sleep poorly, and the finding that their parents report sleep disturbance two to three times as often as other parents, come from parent report. The experiments that produced measurable changes in children’s thinking used actigraphy. A parent outside a bedroom door observes settling and waking; actigraphy yields sleep efficiency, the percentage of time in bed actually spent asleep. The two do not always agree, which is a reason a clinician asking about a child’s sleep may want more than a description of bedtime.

Expert consensus for children aged six to twelve is nine to eleven hours a night. The margin that alters performance is small: the Sadeh experiment shifted its outcome on a difference of a little over half an hour.

Children who sleep poorly differ from children who sleep well in temperament, in household circumstance and in the presence of other conditions, and any of those could account for a difficult afternoon at school.

Sleep is worth protecting for reasons already established: attention, mood, impulse control, the ordinary quality of a school day. Whether it also reaches how a child reads a friend’s face is an open question with a plausible case behind it and no data underneath it. If your child’s nights improve and the friendships do not follow, nothing has gone wrong. That promise was never made.