Teenagers who consistently surrender to slumber earlier than their peers—and remain in it longer—are showing sharper intellect and excelling in brain-powered challenges, say researchers with fresh insights into adolescent neurodevelopment.
Drawing from an extensive study involving 3,222 adolescents, the analysis found that those who shut their eyes the earliest racked up the most sleep and experienced the calmest heart rates while sleeping consistently rose above their peers in tests measuring reading skills, vocabulary strength, and problem-solving capacity.
Though scientists anticipated improved scores from better-sleeping teens, the degree to which even modest differences in rest influenced mental sharpness took them by surprise.
“We’re inclined to believe that better sleep is fueling this cognitive advantage—partly because memory storage and mental organizing happen during deep sleep cycles,” explained Barbara Sahakian, a seasoned professor of clinical neuropsychology at the University of Cambridge.
It’s long been understood that a full night’s rest aids mental clarity, yet what happens during adolescence—a critical time of brain restructuring and a tendency toward later nights—remains a mystery researchers are still trying to unravel.
Sahakian’s team joined forces with Fudan University in Shanghai, diving deep into data from the Adolescent Brain Cognitive Development (ABCD) study—the largest and most ambitious long-term look at youth brain development and well-being in the U.S. These young participants underwent brain scans, mental agility tests, and wore Fitbits to monitor their sleep rhythms.
Interestingly, not even the teens with the best rest routines managed to meet expert recommendations. The American Academy of Sleep Medicine states that 13- to 18-year-olds should aim for between 8 and 10 hours of nightly rest.
The data sorted these adolescents into three categories. The first group—roughly 39%—went to bed late and rose early, snagging an average of 7 hours and 10 minutes of nightly sleep. The second cluster, making up about 24%, secured a slightly better 7 hours and 21 minutes. The final cohort, around 37%, drifted off earliest, stayed asleep the longest, and maintained the calmest sleep-phase heartbeats—averaging around 7 hours and 25 minutes per night.
Though all groups were similar academically, group three dominated when it came to cognitive performance. Group Two trailed behind, with Group One posting the lowest scores. Brain imaging revealed that those in group three had notably more developed brain regions and stronger neural activity. These findings are detailed in the journal Cell Reports.
Sahakian highlighted how unexpected the findings were: “It’s eye-opening to see that even tiny differences in sleep can ripple into major variations in mental capacity. It suggests that the effects of small sleep improvements accumulate over time.”
For teens aiming to sharpen their minds, Sahakian suggests steady physical activity to aid rest, and staying away from screens as the evening sets in.
Commenting on the findings, Colin Espie, a sleep medicine professor at the University of Oxford, noted: “One cost of having such sophisticated brains, capable of complex operations, is that we humans lean heavily on sleep—especially while growing.”
Espie added, “The habit of staying up late and skimping on sleep is problematic. This becomes worse on school days when early rising is non-negotiable, leading to weekend oversleeping—a behavior dubbed ‘social jet lag.’”
He advocated for a cultural shift, “We’d do well to prioritize sleep education in secondary schools, embedding sleep wellness in personal and social learning. Oxford’s Teensleep initiative is already mapping out ways to foster better rest among teens.”
Echoing this, Gareth Gaskell, a psychology professor at the University of York, praised the focus on younger adolescents. “We need more actionable studies during this life stage. Often, small tweaks—especially those tied to screen use—can work wonders on bedtime consistency and overall sleep quality.”