Cognition and objectively measured sleep duration in children: a systematic review and meta-analysis.

Background: Sleep recommendations are widely used to guide communities on children's sleep needs. Following recent adjustments to guidelines by the National Sleep Foundation and the subsequent consensus statement by the American Academy of Sleep Medicine, we undertook a systematic literature search to evaluate the current evidence regarding relationships between objectively measured sleep duration and cognitive function in children aged 5 to 13 years.

Methods: Cognitive function included measures of memory, attention, processing speed, and intelligence in children aged 5 to 13 years. Keyword searches of 7 databases to December 2016 found 23 meeting inclusion criteria from 137 full articles reviewed, 19 of which were suitable for meta-analysis.

Results: A significant effect (r = .06) was found between sleep duration and cognition, suggesting that longer sleep durations were associated with better cognitive functioning. Analyses of different cognitive domains revealed that full/verbal IQ was significantly associated with sleep loss, but memory, fluid IQ, processing speed and attention were not. Comparison of study sleep durations with current sleep recommendations showed that most children studied had sleep durations that were not within the range of recommended sleep. As such, the true effect of sleep loss on cognitive function may be obscured in these samples, as most children were sleep restricted.

Conclusions: Future research using more rigorous experimental methodologies is needed to properly elucidate the relationship between sleep duration and cognition in this age group.