At first sight
- Pre-teens who slept less than nine hours a day had differences in brain structure and more mood and thinking problems than those who slept enough.
- The findings suggest that sleep interventions may be needed to help improve mental and behavioral health during pre-adolescence and beyond.
Scientists have long recognized that getting enough sleep in childhood can promote brain development. However, the underlying brain mechanisms are not well understood. And although experts say children between the ages of 6 and 12 should sleep at least nine hours a day, it’s unclear how 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 decided to see how sleep deprivation affects brain structure and other findings. They leveraged data collected in the ongoing NIH Adolescent Brain Cognitive Development (ABCD) study. ABCD has enrolled nearly 12,000 volunteers aged 9 or 10 from research sites across the country. Participants’ health, structure and brain function and other factors will be tracked for a decade as they progress from adolescence to young adulthood.
The researchers identified more than 4,000 ABCD participants, ages 9 to 10, who typically slept nine or more hours a day, according to their parents. This group was compared with a similar number of children of the same age who typically slept less than the recommended nine hours. The research team carefully matched the two groups based on a few key factors that can confuse the study results. These factors included gender, family income, body mass index, and puberty status. Participants were evaluated and followed up for a period of two years. The results appeared in Lancet Child and Adolescent Health on July 29, 2022.
The researchers found that children in the insufficient sleep group at the start of the study had more mental health and behavioral problems than those who slept enough. These included impulsivity, stress, depression, anxiety, aggressive behavior, and thinking problems. The children with insufficient sleep also had impaired cognitive functions such as decision making, conflict resolution, working memory and learning. Differences between groups persisted at the two-year follow-up.
Brain imaging at the start of the study and two years later showed differences in brain structure and function in the insufficient sleep group versus the sufficient sleep group. The findings suggest that sleep affects learning and behavior through specific brain changes.
“Children who had insufficient sleep, less than nine hours per night, at the start of the study had less gray matter or volume in certain areas of the brain responsible for attention, memory and inhibition control, compared to those with healthy sleep habits, “explains Wang.” These differences persisted after two years, a troubling finding that suggests long-term harm for those who don’t get enough sleep. “
As the ABCD study is ongoing, the researchers note that there will be opportunities to add additional follow-up measurements and build on their findings. “More studies are needed to confirm our findings and to see if any interventions can improve sleep habits and reverse neurological deficits,” adds Wang.
—By Vicki Contie
Financing: 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).