Teenagers who are night owls are more likely to have difficulty regulating their behavior, a new study from the American Academy of Pediatrics (AAP) reports.

Adolescents who were sleepy during the day and more alert in the evening hours ranked low on measures of self-regulation – the ability to alter behavior, thoughts, and emotions depending on the situation. Learning how to self-regulate is an important skill for teenagers to develop, and with chronic fatigue preventing it, the answer may be pushing school start times back to a more reasonable hour.

The study by researchers at Boston Children’s Hospital and Tulane University aimed to find out if chronotype (the tendency to be a “night owl” or a “morning lark”), daytime sleepiness, and number of hours slept per night were associated with the ability to self-regulate.

A sample of 2000 12- to 18-year-old students were asked if they had problems similar to the ones in statements such as “I don’t plan ahead for school assignments,” “I get upset over small events,” or, “It bothers me when I have to deal with changes.” Participants who reported that they often experienced these or similar occurrences were rated as having less self-regulation.

Study participants were also asked questions about the number of hours slept per night, how awake they felt at different points in the day, if they ever fell asleep during school, and if they had difficulty staying awake during the day.

The researchers found that students who were more alert in the evenings and sleepier during the daytime were more likely to have difficulty self-regulating. The sheer number of hours slept at night, however, was not associated with self-regulation.

Adolescents require eight to 10 hours of sleep a night, but the average high school student gets far less. By their senior year in high school, 75% of students are sleeping fewer than eight hours per night, significantly less than the 8.5 – 9.5 hours a night recommended by the National Sleep Foundation.

This widespread fatigue among adolescents has its consequences, with the AAP regarding it as a public health issue. A lack of sleep can have serious health consequences beyond simply feeling tired. Sleep loss has a significant impact on mental health, with teens who are overtired being at a greater risk for depression and suicidal ideation. Insufficient sleep can also increase the risk of obesity, and puts teenagers at a greater risk for driving accidents where drowsiness is a major contributing factor.

And, as this study suggests, a lack of sleep can also have an impact on a teen’s ability to regulate their behavior and emotions.

Learning self-regulation in adolescence relates to better outcomes in adulthood, including better physical health, financial success, less criminality, and less substance abuse. With a lack of sleep impairing students’ capabilities, teenagers aren’t best equipped to manage their thoughts, emotions, and behavior at a time when their actions may begin to have life-long consequences.

So should we just start making teenagers go to bed earlier? It might not help. Researchers found that the number of hours slept per night was not associated with better self-regulation, however, having night owl tendencies did mean more difficulty controlling emotions and behavior.

This correlation means that teenagers who are at their most alert in the evening experience circadian misalignment when forced to start school early in the morning. With teenagers experiencing a natural shift in their sleep patterns, many cannot fall asleep before 11 p.m., meaning there’s no way they can achieve the recommended amount of sleep and be at school by 7 a.m.

When high school and middle schools start before 8:30 a.m., teenagers are at their lowest level of alertness. Waking early likewise causes them to miss out on rapid eye movement (REM) sleep, which is critical for knowledge retention. Trying to squeeze extra hours of learning into the early morning could actually be causing teenagers to learn less overall.

Nationwide, only 14 percent of high schools start after 8:30. Opponents of moving school start times later cite difficulty in managing bus schedules, after-school jobs and sports, and parents’ work schedules. But the benefits of pushing start times are clear.

High schools that push start times back see significant improvement in student achievement. A study of five school districts in three states with later school start times found that students, unsurprisingly, were more likely to sleep eight hours or more each night. The later start times also led to improvement in school attendance, reduced tardiness, and higher national achievement test scores. Students were also more likely to report that they were in good health, and less likely to report being depressed or to use alcohol, tobacco, or other drugs.

According to Start School Later, a non-profit organization that advocates for later start times, early morning classes also may play a hand in widening the achievement gap between low and high income students. Public schools are more likely than private schools to start before 8 a.m., and parents with inflexible working schedules are often unable to make accommodations for a child who overslept and missed the bus.

Teenagers are at a point in life where they’re given more freedom and responsibility than ever before. Learning to navigate these new opportunities can be challenging even under ideal circumstances. When you add in the hurdle of chronic sleep deprivation caused by early school start times, it’s easy to see why teens would struggle to regulate their thoughts, emotions, and behaviors.

While moving school start times later than 8:30 might require the shuffling around of schedules and a good deal of logistical rearranging, it could be just the thing teenagers need to improve their physical and mental health.