23-04-2025
Think sleep doesn't matter? New study shows early-bed teens outperform their peers
Dubai: For many of us, bedtime as children was non-negotiable - parents enforced strict lights-out rules with one core message: if you want to do well in school, you need a good night's sleep. As it turns out, they may have been right all along.
A new study, published on April 16 in the scientific journal Cell Reports, has reinforced the idea that sleep is crucial for cognitive performance in teenagers. Conducted by researchers from Fudan University in Shanghai and the University of Cambridge, the study monitored the sleep habits of over 3,000 adolescents and found that those who went to bed earlier, slept longer, and had lower heart rates during sleep consistently outperformed their peers in cognitive tasks such as reading, vocabulary, and problem solving.
'Regularly getting a good night's sleep is important in helping us function properly,' said Professor Barbara Sahakian from the Department of Psychiatry at the University of Cambridge, one of the study's authors. 'While we know a lot about sleep in adulthood and later life, we know surprisingly little about sleep during adolescence, even though this is a crucial time in our development.'
The research drew on data from the Adolescent Brain Cognitive Development (ABCD) Study, the largest long-term investigation into brain development and child health in the United States. Previous studies in this area often relied on self-reported sleep patterns, which can be unreliable.
To overcome this, researchers used wearable fitness trackers (FitBits) to collect objective sleep data from more than 3,200 participants aged between 11-12 years old. These adolescents also underwent brain scans and cognitive assessments. To validate their findings, the researchers cross-checked the results with two additional groups of 13- to 14-year-olds, totalling around 1,190 participants.
The team identified three distinct sleep pattern groups:
Group One (39 per cent of participants) slept an average of 7 hours and 10 minutes. They tended to go to bed the latest and woke up the earliest.
Group Two (24 per cent) had a slightly longer average sleep duration of 7 hours and 21 minutes, with average sleep timing.
Group Three (37 per cent) clocked the longest average sleep - 7 hours and 25 minutes and went to bed the earliest. They also recorded the lowest sleeping heart rates.
While academic performance at school did not significantly differ across the three groups, the cognitive test results told another story. Group Three, the earliest sleepers with the most rest and lowest heart rates outperformed both Group Two and Group One on tasks related to memory, vocabulary, reading, and focus.
Professor Sahakian described the findings as 'surprising', telling The Guardian that even relatively minor differences in sleep accumulated over time to make a substantial difference in outcomes.
Dr Qing Ma from Fudan University, another lead author, added: 'Although our study can't conclusively prove that better sleep causes improved brain function, there is a growing body of research suggesting this link. For instance, sleep has well-documented benefits for memory consolidation, which plays a vital role in learning.'
The study also examined the participants' heart rates during sleep, another strong indicator of sleep quality. Lower heart rates, as seen in Group Three, are often associated with better sleep and overall health. Conversely, higher heart rates can signal restless sleep, frequent awakenings, or poor sleep quality.
