Research finds that sleeping less than nine hours a night is associated with cognitive difficulties, mental problems and less gray matter in certain regions of the brain
Summary Background Although the American Academy of Sleep Medicine suggests at least 9 hours of sleep per day for children ages 6 to 12, children in recent generations often report sleeping less than this amount. Because early adolescence is a crucial period for neurocognitive development, we aimed to investigate how sleep deprivation affects children’s mental health, cognition, brain function, and brain structure over 2 years. Methods In this propensity score-matched longitudinal observational cohort study , we obtained data from a population-based sample of 9- to 10-year-old children from 21 US sites in the ongoing Adolescent Brain Cognitive Development (ABCD) study. ). Participants were classified as getting enough sleep or not enough sleep based on a cutoff of 9 hours of sleep per day. Using propensity score matching, we matched these two groups of participants on 11 key covariates, including sex, socioeconomic status, and pubertal status. Participants were excluded from our analysis if they did not pass a baseline resting-state functional MRI quality check or if they had missing data for covariates involved in propensity score matching. Outcome measures retrieved from the ABCD study were behavioral problems, mental health, cognition, and structural and resting-state functional brain measures, assessed at baseline and 2-year follow-up. We examined group differences in these outcomes over those 2 years among all eligible participants. We then did mediation analyzes of the neural correlates of sleep deprivation-induced behavioral changes. Results Between September 1, 2016 and October 15, 2018, baseline data for the ABCD study were collected from 11,878 people , of whom 8,323 were eligible and included in this study (4,142 participants in the sufficient sleep group and 4,181 in the insufficient sleep group). Follow-up data were collected from July 30, 2018 to January 15, 2020. We identified 3021 sufficient sleep-insufficient sleep matched pairs at baseline and 749 matched pairs at 2 years of follow-up, and observed similar differences between groups on behavioral and neural measures at both time points; The effect sizes of between-group differences on behavioral measures at these two time points were significantly correlated with each other (r = 0.85, 95% CI: 0.73–0.92; p < 0.0001 ). A similar pattern was observed in resting-state functional connectivity (r=0·54, 0·45–0·61; p<0·0001) and in structural measures (e.g., volume of matter gray r=0·61, 0·51–0·69; p<0·0001). We found that functional connections of the corticobasal ganglia mediate the effects of insufficient sleep on depression, thinking problems, and crystallized intelligence, and that structural properties of the anterior temporal lobe mediate the effect of insufficient sleep on crystallized intelligence. Interpretation These results provide population-level evidence for the lasting effect of insufficient sleep on neurocognitive development in early adolescence. These findings highlight the value of early sleep intervention in improving long-term developmental outcomes of early adolescents. |
Image : The images show differences in gray matter volume (red areas) between children who got enough sleep and those who did not sleep both at the beginning of the study and at a two-year follow-up visit. Areas highlighted in red are structures responsible for decision making, impulse control, memory, and mood regulation.
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Elementary school-aged children who sleep less than nine hours a night have significant differences in certain brain regions responsible for memory, intelligence and well-being compared to those who sleep between the recommended nine and 12 hours a night, according to a new study led by researchers at the University of Maryland School of Medicine (UMSOM).
Such differences were correlated with greater mental health problems, such as depression, anxiety and impulsive behaviors, in sleep deprived people. Inadequate sleep was also linked to cognitive difficulties with memory, problem solving, and decision making. The findings were published in the journal Lancet Child & Adolescent Health .
The American Academy of Sleep Medicine recommends that children ages 6 to 12 get 9 to 12 hours of sleep per night regularly to promote optimal health. So far, no studies have examined the lasting impact of sleep deprivation on preteens’ neurocognitive development.
To conduct the study, researchers examined data collected from more than 8,300 children ages 9 to 10 who were enrolled in the Adolescent Brain Cognitive Development (ABCD) study. They examined MRI images, medical records, and surveys completed by participants and their parents at enrollment and at a two-year follow-up visit at ages 11 or 12. Funded by the National Institutes of Health (NIH), the ABCD study is the largest long-term study of brain development and childhood health in the US.
"We found that children who had not gotten enough sleep, less than nine hours a night, at the beginning of the study had less gray matter or a smaller volume in certain areas of the brain responsible for the control of attention, memory and inhibition in compared to those with healthy sleep,” said study corresponding author Ze Wang, PhD, Professor of Diagnostic Radiology and Nuclear Medicine at UMSOM. “These differences persisted after two years , a worrying finding that suggests long-term harm for those who do not get enough sleep.”
This is one of the first findings to demonstrate the potential long-term impact of sleep deprivation on children’s neurocognitive development. It also provides substantial support for current recommendations on children’s sleep, according to Dr. Wang and his colleagues.
In follow-up evaluations, the research team found that participants in the sufficient sleep group tended to gradually sleep less over two years, which is normal as children transition into adolescence, while sleep patterns of Participants in the insufficient sleep group did not change much. The researchers controlled for socioeconomic status, gender, pubertal status and other factors that could affect how much sleep a child gets and affect the brain and cognition.
“We tried to match the two groups as closely as possible to help us better understand the long-term impact of sleep deprivation on the preteen brain,” Dr. Wang said. “Additional studies are needed to confirm our finding and see whether any intervention can improve sleep habits and reverse neurological deficits."
The American Academy of Pediatrics encourages parents to promote good sleep habits in their children. Their tips include making getting enough sleep a family priority, following a regular sleep routine, encouraging physical activity during the day, limiting screen time, and eliminating screens completely an hour before bedtime.
"This is a crucial study finding that points to the importance of conducting long-term studies on the developing child’s brain," said E. Albert Reece, MD, PhD, MBA, executive vice president of Medical Affairs, UM Baltimore, and John Z. and Akiko K. Bowers Distinguished Professor and Dean of the University of Maryland School of Medicine. "Sleep can often be overlooked during the busy days of childhood filled with chores and extracurricular activities. We now see how detrimental it can be to a child’s development."
The study was funded by NIH. Fan Nils Yang, PhD, a postdoctoral fellow in Dr. Wang’s lab, is a co-author of the study. Weizhen Xie, PhD, a researcher at the National Institute of Neurological Disorders and Stroke, is also a co-author of the study. UMSOM faculty members Thomas Ernst, PhD, and Linda Chang, MD, MS, are co-principal investigators of the ABCD study at the Baltimore site, but were not involved in data analysis for this new study.
