At a glance
- Teenagers who slept less than nine hours a day had changes in brain structure and more problems with mood and thinking compared to those who got enough sleep.
- The findings suggest that sleep interventions may be needed to help improve mental and behavioral health during preadolescence and beyond.
Scientists have long known that getting enough sleep during childhood can benefit the developing brain. However, the underlying brain mechanisms are not well understood. And although experts say children ages 6 to 12 should get at least nine hours of sleep each day, it’s been unclear how much less sleep can affect a child’s brain.
To get some answers, a research team led by Dr. Ze Wang of the University of Maryland tried to see how sleep deprivation affects brain structure and other outcomes. They took advantage of data collected in the NIH’s ongoing Adolescent Brain Cognitive Development (ABCD) study. ABCD has enrolled nearly 12,000 volunteers at age 9 or 10 from research sites across the country. The participants’ health, brain structure and function, and other factors will be followed for a decade as they transition from adolescence to young adulthood.
Researchers identified more than 4,000 ABCD participants, ages 9 or 10, who generally slept nine or more hours a day, according to their parents. This group was compared to a similar number of age-matched children who typically slept less than the recommended nine hours. The research team carefully compared the two groups based on several key factors that could confound the study results. These factors included sex, family income, body mass index, and puberty status. Participants were evaluated and followed over a two-year period. The results appeared in Lancet Child and Adolescent Health on July 29, 2022.
The researchers found that children in the sleep-deprived group at the start of the study had more mental health and behavioral problems than those who got enough sleep. These included impulsivity, stress, depression, anxiety, aggressive behavior and thinking problems. Children with insufficient sleep also had impaired cognitive functions such as decision making, conflict resolution, working memory and learning. Differences between groups persisted during the two-year follow-up.
Brain imaging at the start of the study and two years later showed changes in brain structure and function in the sleep-deprived group compared to the sleep-sufficient group. The findings suggest that sleep affects learning and behavior through specific brain changes.
“Children who had insufficient sleep – less than nine hours a night – at the start of the study had less gray matter or smaller volume in certain areas of the brain responsible for attention, memory and inhibitory control, compared to those with healthy sleeping habits. ”, explains Wang. “These differences persisted after two years, a disturbing finding that suggests long-term harm to those who don’t get enough sleep.”
Because the ABCD study is ongoing, the researchers note that there will be opportunities to add more follow-up measurements and build on their results. “Additional studies are needed to confirm our findings and to see if any intervention can improve sleep habits and reverse neurological deficits,” adds Wang.
—by Vicki Contie
Funding: NIH’s National Institute on Aging (NIA), National Institute of Biomedical Imaging and Bioengineering (NIBIB), National Center for Advancing Translational Sciences (NCATS), and National Institute on Drug Abuse (NIDA).