An idea that seems to make sense
The idea that sleep impacts on learning has plenty of intuitive weight, simply because everyone has experienced feeling tired and unable to concentrate, but the science behind this is quite new and really interesting. There are basically two ways to look at the relationship between sleep and learning (or school performance): firstly by considering what happens when children don’t get enough sleep, and secondly by assessing the science of what sleep does for the brain.
Firstly, a brief anatomy of sleep. There are two broad stages of sleep- rapid eye movement (REM) and non-rapid eye movement (NREM). When we fall asleep, we slip through stages one and two of NREM and into the deep sleep stages three and four, where brain activity is at its slowest, before moving into REM sleep, at which point brain activity becomes much more rapid, and if we are awakened we often report experiencing dreams. Adults cycle through these stages roughly every 90 minutes, while for infants it’s more like every 30-50 minutes. In children under two, and indeed in all young mammals, a much higher proportion of REM sleep is seen, leading some to suggest that the main role of REM sleep is supporting brain development. In older children NREM is more dominated by stages two and three, or ‘slow wave sleep’, again suggesting that slow wave activity in the brain might be especially associated with learning.
Sleep deprivation stunts learning
There are a few studies looking at the effects that short-term sleep deprivation has on the behaviour of typically developing children and adolescents. The research on sleep deprivation in children typically looks at the relationship between how well children sleep and their performance at school the next day. In 9-14 year olds, good sleep quality, feeling rested at school and having a distinct bed time have been associated with better functioning at school[i], while 10-14 year olds deprived of sleep for a single night have shown deficits in abstract thinking and verbal creativity[ii]. Looking over the course of a week, just one hour of sleep deprivation each night in 6-8 year olds resulted in changes in brain activity during simple tasks of attention and speech perception[iii]. So both chronic and acute sleep deprivation make an impact on how children function during the school day.
Brain imaging has shown that after chronic sleep deprivation in adolescents, brain areas that actively maintain attention have to work much harder to sustain performance during a memory task[iv]. So even those children who keep up performance at school may be working much harder to do so after a poor night’s sleep.
Sleep consolidates learning …
Sleep is thought to be an active part of learning, with around 83% of published studies showing an association between sleep and memory[v]. Studies looking at the role of sleep in learning tend not to deprive participants of sleep, but rather teach them a task, then test them after a set interval which is either filled with normal sleep (over night or a daytime nap) or being awake; that way participants can be compared with one another the same amount of time after learning the task, but with only half the group having slept. In adults, sleep benefits all types of memory task tested. Broadly speaking, memory tasks can either be explicit, where the participant knows they are learning and actively does so, such as learning to associate word pairs, or they can be implicit, where the participant tends to be unaware they are learning, for example repeatedly performing a cued finger tapping sequence or other motor task[vi]. Explicit learning is supported by slow wave sleep during NREM periods and implicit learning is believed to be more supported by REM sleep[vii]. Indeed, boosting slow electrical activity in the brain artificially by applying a weak electric field to the head during sleep was found to actively increase explicit memory performance[viii]!
… in children, too
In children, explicit memory is supported by sleep, just like in adults, but implicit memory may not be[ix]. There’s not as much work looking at the impact of sleep on learning and memory with children as there is with adults and seemingly no studies looking at, for example, the impact of a good night’s sleep on exam performance. However, we know that sleep improves explicit memory, and performance in exams generally relies on remembering facts, which is an explicit task and is therefore likely to be sleep-dependent.
Interestingly, 75-80% of children with neurodevelopmental disorders (including Autism, epilepsy, cerebral palsy and ADHD) have chronic sleep disturbance, including difficulty falling asleep, frequently waking in the night and waking early in the morning. However, there’s very little research into the relationship between sleep and learning in these groups of children.
So get a good night’s sleep
The verdict here is a resounding neuro-hit. The extent to which sleep impacts on learning depends on the degree and duration of sleep deprivation and type of material being learned; but yes, well-rested children will perform better in the classroom in the short-term and the long-term.
Dr Robert Stickgold talks about sleep and memory at TEDx.
[iii] Molfese, D. L., Ivanenko, A., Key, A. F., Roman, A., Molfese, V. J., O’Brien, L. M., Gozal, D., Kota, S., & Hudac, C. M. (2013). A one-hour sleep restriction impacts brain processing in young children across tasks: evidence from event-related potentials. Developmental Neuropsychology, 38 (5), 317-336. doi: 10.1080/87565641.2013.799169.
[iv] Beebe, D. W., Difrancesco, M. W., Tlustos, S. J., McNally, K. A., Holland, S. K. (2009). Preliminary fMRI findings in experimentally sleep-restricted adolescents engaged in a working memory task. Behavioural and Brain Functions, 9; 5-9. doi: 10.1186/1744-9081-5-9.
[vii] Marshall, L., & Born, J. (2007). The contribution of sleep to hippocampus-dependent memory consolidation. Trends in Cognitive Sciences, 11(10), 442-450.