How sleep affects the development of the brain: A longitudinal perspective on neurological development and sleep
The American Academy of Sleep Medicine (AASM) recommends at least 9 hours of sleep per day for 6–12-year-olds. However, it’s reported that recent generations of children are sleeping less and less. Primary school-aged children who sleep too little can develop a range of psychological and medical problems.
This is what researchers at the University of Maryland School of Medicine found when they examined the data of over 8,000 children ina recent longitudinal studyrecently published in the scientific journal, The Lancet1.
This is one of a number of studies undertaken by the University to demonstrate the potential long-term effects on neurocognitive development in children who sleep less than the recommended amount2.
Performed by Fan Nils Yang and colleagues, the study evaluated the data of 8,323 girls and boys aged 9-10 years at commencement. Researchers determined how long the children slept on average per night by interviewing their parents. Based on AASM recommendations researchers classified the children as getting sufficient or insufficient sleep.
The children undertook cognitive performance testing as well as psychological and medical examinations, including functional magnetic resonance imaging (fMRI). This data was measured out the outset of the study, to establish a baseline, and again two years later to compare the results.
Comparing sufficient and insufficient sleep clusters
Participants were grouped into two clusters – the first containing children with sufficient sleep, and the second containing those with insufficient sleep based on the AASM recommendation of 9 hours.
These clusters were further sub-categorised around several covariates including sex, socioeconomic status, and puberty status. According to researcher Dr. Wang, the aim was to “Match the two groups as closely as possible to better understand the long-term effects of insufficient sleep on the brain before puberty”. This enabled researchers to account for the impact of these factors on the findings so variations could be exclusively attributed to differences in sleep behaviour2.
When evaluating the data, researchers identified differences in the volume of grey brain matter in fMRI data after 2 years, respective to the baseline measures. They also identified behavioural abnormalities and cognitive deficits.
“Participants in the sufficient sleep group tended to gradually sleep less over the two years, which is normal as children move into their teen years, whereas sleep patterns of participants in the insufficient sleep group did not change much” says, Dr. Wang.
In tests on memory, decision-making and problem-solving skills, children who slept too little performed more poorly than their well-rested peers. Impulsive behaviour, depression, and anxiety also occurred more frequently in those with insufficient sleep.
“We found that children who had less than nine hours of sleep per night at the beginning of the study had less grey matter or volume in certain areas of the brain responsible for attention, memory and impulse control than children with healthy sleep habits.”
Ze Wang, Ph.D, University of Maryland School of Medicine
“We found that children who had less than nine hours of sleep per night at the beginning of the study had less grey matter or volume in certain areas of the brain responsible for attention, memory and impulse control than children with healthy sleep habits”, stated Wang. “These differences were still detectable even two years later. This is a worrying finding because it suggests long-term damage in the children who do not get enough sleep”2.
The impact of sleep on behaviour and functional anatomy
By conducting a 2-year longitudinal study researchers were able to identify changes in behaviour and functional anatomy that were clearly correlated with differences in sleep behaviour. The study highlights the importance of sleep for cognitive development especially in puberty – a critical period of brain development.
Many factors contribute to poor sleep, in particular blue spectrum lightplays an important role in sleep-wake cycles, regulating the circadian rhythm. While exposure to blue spectrum light from the sun is important in the morning to calibrate the body’s internal clock, in the evening it should be avoided to signal that it is night and time to wind down.
In recent years there has been an increasing use of display technologies which emit blue light late into the evening, and this has become a major factor contributing to reduced sleep quality.
Steps to improve sleep quality in children
The American Academy of Pediatrics suggests several tips to promote good sleep habits in children. These include
Making adequate sleep a family priority
Sticking to a regular sleep routine
Encouraging physical activity during the day
Limiting screen time, and
Turning off all monitors an hour before bedtime.
Commenting on the study, neurocare’s UK-based clinician Silvia Bucciarelli adds that it is important to make “early sleep interventions to improve long-term developmental outcomes in adolescents”. She continues that it is central to not only focus on sleep duration but also sleep quality and the factors influencing it. Such factors include exposure to blue light, nutrition and exercise.
Whether part of a mental illness or is an issue of its own, it is important to appreciate sleep and understand its important connection to our health and wellbeing. Neurocare incorporates sleep assessments as part of our intake procedure and offers support for people who need extra help in “quietening“ their minds and regulating brain activity.