A good night’s sleep isn’t just about feeling rested – it’s vital for the developing brains of teenagers, according to new research from the University of Cambridge and Fudan University. The study, published in Cell Reports, suggests that even modest increases in sleep duration can lead to improved cognitive performance and better brain health in adolescents.
Researchers analysed data from over 3,200 children aged 11-12, and a further 1,190 aged 13-14, as part of the ongoing Adolescent Brain Cognitive Development (ABCD) Study – the largest long-term study of its kind in the United States. Participants wore FitBits to meticulously track their sleep patterns. The team then correlated this data with cognitive test results and brain scans.
The children were broadly categorised into three groups based on their average sleep duration. The largest group (37%) averaged 7 hours and 25 minutes of sleep, going to bed earliest, while another 24% slept for an average of 7 hours and 21 minutes. The remaining 39% averaged 7 hours and 10 minutes, tending to have the latest bedtimes and earliest wake-up times.
While school achievement didn’t significantly differ between the groups, clear distinctions emerged in cognitive performance and brain health. The group with the longest sleep duration consistently outperformed the others in tests assessing vocabulary, reading comprehension, problem-solving skills, and focus. This group also exhibited larger brain volume and superior brain function, while the shortest sleepers showed the opposite trends.
“Even though the differences in sleep duration were relatively small – just over a quarter of an hour between the best and worst sleepers – we could still see differences in brain structure, activity, and cognitive performance,” explained Professor Barbara Sahakian from Cambridge University’s Department of Psychiatry. “This drives home just how important a good night’s sleep is during this crucial time of life.”
The researchers also noted physiological differences. The group sleeping the longest had the lowest heart rates during sleep—generally a sign of better health—while the shortest sleepers had the highest, potentially indicating poorer sleep quality. The study reinforces existing research pointing to the link between sleep and memory consolidation – vital for learning.
Senior author Dr Wei Cheng from Fudan University is now turning attention to the root causes of sleep discrepancies. “We now need to investigate why some children go to bed later and sleep less,” he stated. “Is it due to factors like screen time, or simply differences in their biological clocks?”
The long-term nature of the ABCD study allows researchers to track changes over time and provides strong evidence that these sleep patterns, brain structure, function and cognitive performance are consistent over time. This research offers a compelling argument for prioritising sleep as a key component of adolescent health and development.
