Teens Who Go to Bed Earlier Have Sharper Brains, Study Finds

During adolescence, sleep goes through many changes, and this directly affects brain development. A study with thousands of adolescents showed that those who sleep better (earlier, longer and with lower heart rates) have better brain development and cognitive performance. These findings reinforce how good sleep habits are essential for the healthy growth of the body and mind.

Sleep is fundamental to our health and well-being. It not only helps keep the body functioning well, but it is also essential for brain development and the good performance of mental functions, such as learning, remembering, making decisions and controlling emotions.

During adolescence, it is common for sleep patterns to change. Young people tend to sleep less, take longer to fall asleep and tend to go to bed later than when they were children.

These changes are part of growth and occur at the same time that the brain is undergoing several important transformations. Therefore, understanding how sleep relates to the development of the brain and mind at this stage is very important.

Some studies have shown that certain sleep characteristics may be linked to brain structure and function in adolescents. However, most of these studies rely on self-reporting from adolescents, which can be inaccurate, and many young people end up exaggerating or misrepresenting their sleep habits.

In addition, these studies often only look at one aspect of sleep at a time, which makes it difficult to understand the full picture.

Today, with the help of technologies such as smartwatches (like Fitbit), scientists can measure sleep in a more objective and detailed way.

This includes not only sleep duration, but also heart rate, the time at which a person falls asleep, and the time spent in different stages of sleep. Still, many studies using these technologies still have small numbers of participants, which limits the strength of the conclusions.

In this new study, researchers analyzed data from more than 3,000 adolescents from a large U.S. project called ABCD (Adolescent Brain Cognitive Development).

They used an advanced data analysis technique called sCCA (sparse canonical correlation analysis) to find patterns between sleep characteristics and brain scans in these young people.

This image is a visual summary of the study that investigated how adolescent sleep is linked to brain development and cognitive skills (such as memory, attention, and academic performance).

1. Participants: The researchers followed thousands of adolescents at two time points: first between ages 11 and 12, and then between ages 13 and 14.

   
   

2. What they measured: They used smartwatches (like Fitbits) to track how the teens slept over a 3-week period, such as how long they slept, what time they fell asleep, and their heart rate during sleep. They also used brain scans to analyze the size and activity of various parts of the brain.

Objective 1: Find out how sleep affects the brain

They used an advanced type of analysis to find patterns between how teens slept and changes in their brains. For example, they found that sleeping later and for shorter periods was linked to weaker brain connections.

Objective 2: Understand the consequences of this

Based on these patterns, the adolescents were divided into three groups (“biotypes”) with different sleep, brain and cognitive characteristics. One group, for example, slept earlier and for longer, and this group had better cognitive outcomes over time.

The researchers found two main links between sleep and the brain. The first showed that teens who sleep less and go to bed later tend to have weaker communication between important brain regions.

The second revealed that those who have a higher heart rate during sleep (which may indicate poorer quality of rest) also tend to have smaller brain volumes and less connectivity between brain areas.

Based on these findings, the scientists identified three main groups of sleep patterns (called “biotypes”). One group slept little and late, with higher heart rates during sleep. Another group slept early and for longer, with lower heart rates; this group performed better on tests of reasoning and learning. A third group fell somewhere in between.

The researchers followed these adolescents for a few years, from ages 9 to 14, and found that these sleep patterns were linked to real differences in brain development and academic performance. In other words, the type of sleep a young person gets can significantly influence their mental and academic development.

These results show that sleep is not just a matter of “sleep or no sleep,” but rather a factor deeply linked to brain function.

Understanding these patterns can help parents, educators, and health professionals think of ways to improve adolescents’ sleep habits, which can have direct benefits for learning, memory, mood, and even long-term mental health.

READ MORE:

Neural correlates of device-based sleep characteristics in adolescents

Qing Ma, Barbara J. Sahakian, Bei Zhang, Zeyu Li, Jin-Tai Yu, Fei Li, Jianfeng Feng, Wei Cheng 

Cell Reports. Volume 44, Issue 5115565, May 27, 2025

DOI: 10.1016/j.celrep.2025.115565

Abstract:

Understanding the brain mechanisms underlying adolescent sleep patterns and their impact on psychophysiological development is complex. We applied sparse canonical correlation analysis (sCCA) to data from 3,222 adolescents in the Adolescent Brain Cognitive Development (ABCD) study, integrating sleep characteristics with multimodal imaging. This reveals two key sleep-brain dimensions: one linking later sleep onset and shorter duration to decreased subcortical-cortical connectivity and another associating a higher heart rate and shorter light sleep with lower brain volumes and connectivity. Hierarchical clustering identifies three biotypes: biotype 1 has delayed, shorter sleep with a higher heart rate; biotype 3 has earlier, longer sleep with a lower heart rate; and biotype 2 is intermediate. These biotypes also differ in cognitive performance and brain structure and function. Longitudinal analysis confirms these differences from ages 9 to 14, with biotype 3 showing consistent cognitive advantages. Our findings offer insights into optimizing sleep routines for better cognitive development.