There are a lot of ways that a lack of sleep can affect adults and children, but how does sleeping less affect teenagers? Researchers from the University of California Berkeley’s Golden Bear Sleep and Mood Research Clinic used longitudinal data to examine the effects of staying up late on teenagers. They found that later bedtimes are linked to decreased academic performance at school and to emotional issues in young adulthood.

The researchers utilized data from the National Longitudinal Study of Adolescent Health (NLSAH), sampling a nationally representative cohort of 2,700 U.S. teens aged 13 to 18. NLSAH has been tracking young people since 1994, collecting data at three points: the onset of puberty, a year after puberty, and again upon reaching young adulthood. The longitudinal data was analyzed in conjunction with school transcripts and other education and health data to identify patterns.

According to the results, 30% of middle and high school teens in the sample reported late bedtimes—11:30 PM or later on school nights and 1:30 AM or later in the summer. These night owl teenagers had lower GPAs on average by graduation than their peers who went to sleep earlier. They were also more vulnerable to emotional problems. Furthermore, they found that later bedtimes during the summer did not appear to correlate to lower grades, but there was a relationship between late summer bedtimes and emotional problems in young adulthood.

These findings contribute to the growing debate over having a later start time for middle and high schools. Since teens who go to bed late exhibit worse academic performance (presumably, in part, because they have to wake up so early), some groups see the need for a later school day. This research also corroborates other findings that indicate that a healthy sleep cycle is good for both academics and emotional health.

Although teens naturally tend to have an evening circadian preference, another culprit for late bedtimes, according to the study authors, may be bright lights later in the evening. Too much screen time (with computers, televisions, etc.) can suppress melatonin, a hormone that regulates the sleep cycle. One way for parents to support teens going to bed early is to limit access to electronic devices before bed.

“This very important study adds to the already clear evidence that youth who are night owls are at greater risk for adverse outcomes. Helping teens go to bed earlier may be an important pathway for reducing risk,” stated senior author of the paper Allison Harvey, a psychologist at UC Berkeley.

This research is published in the Journal of Adolescent Health.

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