School Start Times and Sleep

Updated on October 29, 2020

When summer winds down, students nationwide start gearing up to go back to school. While many think about this “back to school” period as the time to stock up on supplies like pencils and notebooks, the reality is that it marks an important transition in the day-to-day schedule of children and teenagers across the country.

Unfortunately, that schedule transition often carries negative consequences for teenagers. During the summer, most teens have the freedom to stay up at night and sleep later in the morning. This isn’t just by choice; it’s a matter of biology and their circadian rhythms.

During the school year, most teens don’t have the ability to follow this natural inclination toward being “night owls.” Instead, the majority of schools in America require them to start class at 8:30 a.m. or earlier. The upshot is that teens get less sleep, which has implications for their physical health, emotional well-being, and academic achievement.

In this guide, we’ll review what the science tells us about teens, sleep, and school start times. We’ll explain why teens sleep the way they do, why later start times can be beneficial, and what parents and other adults can do to help teens try to get the sleep they need.

Teenagers and Sleep

For many people, it is tempting to think that “sleep is sleep,” and that it’s the same for everyone, especially after childhood. The reality, though, is much more complicated.

As a matter of biology and circadian rhythms, sleep is just different for teenagers. These biological differences affect how much sleep teens need, when they sleep best, and the negative impacts when they get insufficient sleep.

Why is Teen Sleep Different?

Sleep is different for teens because of changes to their circadian rhythm. In simple terms, the circadian rhythm refers to the body’s daily schedule or timeline, and the primary factor that influences it is our exposure to light. For sleep and overall health, it’s usually best to have circadian rhythms closely aligned with the local day-night schedule.

For example, in most adults, as night falls, the body starts to produce a hormone called melatonin that helps promote sleep. If a person has a disrupted circadian rhythm, though, their melatonin production may be shifted, making it harder to fall asleep or stay asleep, such as in circadian rhythm sleep disorders.

In teens, there is a normal shift in the circadian rhythm that begins around the start of puberty. During this shift, teenagers’ melatonin product starts later. In addition, they have a delay in their “sleep drive,” which is the internal impulse to go to bed. These two factors combine to make teenagers naturally inclined to stay up later at night and sleep in longer in the morning. They also frequently have more short bouts of sleepiness in the afternoon.

When teens are allowed to sleep according to their own preferred schedule, they often elect to sleep from around 11 p.m. until 8 a.m. Or they may go to bed even later. Overall, though, they still sleep around the same amount; their sleep is just pushed later. Numerous studies have observed this shift of sleep timing that is about two hours later than most children and adults.

These changes are normal and the result of the underlying biology related to puberty. In many cases, though, this natural change to sleep patterns comes into conflict with daily schedule obligations, especially for school.

How Much Sleep Do Teens Need?

The broad recommendation from the American Academy of Sleep Medicine (AASM) is that people between the ages of 13 and 18 should get 8-10 hours of sleep every night. The American Academy of Pediatrics (AAP) offers a slightly narrower range, recommending 8.5 to 9.5 hours per night.

In comparison, the AASM recommends that adults get 7 or more hours of sleep per night.

What Are the Consequences of Sleep Deprivation in Teens?

Getting enough sleep consistently is vitally important for teenagers. Sleep deprivation in teens can have myriad health effects that are described in the sections below.

Physical Well-Being

The body needs sleep to be able to effectively grow, function, and recuperate. Without enough sleep, studies have found that teens are at risk of metabolic problems that affect appetite and can promote obesity. Insomnia in teens may contribute to anorexia nervosa, which can impact both physical and mental health in various ways.

Lack of sleep can affect the heart and cardiovascular system, putting teens at a higher risk of problems like heart disease and diabetes. Skin problems, including acne, are more common with teen sleep deprivation as well.

Another major threat to physical health comes from an elevated risk of accidents related to sleep deprivation. These accidents can occur because of daytime sleepiness and/or slower reactions times, and the most concerning are automobile accidents. The risk for teens from drowsy driving can be even higher given their increased susceptibility to distracted driving.

Learning, Thinking, and Academic Achievement

Sleep plays a central role in our brain’s ability to learn, remember, and utilize information. This information could be made up of simple facts or of broader skills and abilities. In virtually all aspects of cognition and mental acuity, performance is worsened when we’re in the fog of sleep deprivation. Whether it’s classroom learning, hands-on tasks, or creative pursuits, lack of sleep is a detriment.

Studies have found that this reduced cognitive ability manifests in worse academic performance for teens when measured by grades and test scores. Daytime sleepiness and reduced attention have also been found to decrease academic achievement in teens.

Mental Health

Sleep has a complex relationship with many mental health conditions. Lack of sleep can contribute to irritability and overall problems with emotional wellness in both teens and adults. In teens, a lack of sleep has been tied to mood disorders, including depression and bipolar disorder, and to anxiety disorder. Without quality sleep, people with attention-deficit/hyperactivity disorder (ADHD) often experience worse symptoms.

Many of these conditions also have a bidirectional relationship with sleep, meaning that they can make it harder to get normal, quality sleep. In this way, worsening sleep and worsening symptoms can become mutually reinforcing.

Because the brain is at an important point of development during the teenage years, getting good sleep may help to prevent the development of some mental health conditions or may help to reduce the severity of an individual’s symptoms.


One way in which the brain develops during the teenage years is by enhancing its ability to control impulses. This happens as the frontal lobe of the brain grows and develops. When teens don’t get enough sleep, it can reduce the effectiveness of the frontal lobe, leading to more impulsive decision-making. As a result, sleep-deprived teens are often prone to high-risk behaviors related to driving, sexual activity, and the use of alcohol or drugs.


School Start Times: What Does the Data Say?

Most middle and high schools in the United States have a start time of 8:30 a.m. or earlier. Considering that students have to wake up, get ready for school, and arrive in classrooms by that start time, it’s rare for teenagers in these schools to be able to sleep as late as they would like based on their circadian rhythm.

Despite the early start, many teenagers still find that they aren’t ready to sleep until later in the evening. As a result, their total sleep hours are reduced, causing many teens to be sleep deprived. In a survey conducted by the National Sleep Foundation, nearly 60% of 6th through 8th graders and over 85% of high schoolers said that they were getting less sleep than is recommended.

With school start times and teens’ circadian rhythms in conflict, some have proposed that moving start times back could benefit the overall health and academic performance of teens. In this section, we’ll examine what the research to date has indicated to date about this idea.

Individual Schools

In the mid-1990s, seven high schools in Minnesota pushed back start times, and though there were some inconveniences in the transition process as students, teachers, and families adjusted to the new schedule, student achievement was found to have improved.

More recently, a study conducted by University of Washington researchers with two high schools in the Seattle area found meaningful benefits from pushing high school start times back from 7:30 a.m. to 8:45 a.m. On average, students did not stay up later, but they slept more than half an hour more, had better attendance, and improved academic performance.

Pilot projects to change start times for schools in Missouri, Wyoming, and Georgia have found diverse positive results, including fewer attendance problems, increased academic engagement, and fewer teen traffic accidents.

A non-profit organization called Schools Start Later has a repository of success stories that lists information about efforts to push back start times that have taken place in over 45 states.


Meta-analyses are a form of literature review in which researchers examine and summarize a number of existing research studies. Because research studies can have distinct designs and results, a meta-analysis attempts to formulate an apples-to-apples comparison that makes it easier to draw overall conclusions.

These literature reviews for school start times have also pointed to benefits from later starts for teens. For example, a 2016 review of 38 studies found increased sleep duration for teens that was also correlated with less tardiness, better grades, and reduced auto accidents.

Expert Recommendations

Another way to consider the strength of the evidence for later start times is by looking at the recommendations from organizations that represent experts in the field. These organizations base recommendations on input from research studies and extensive experience working with teens.

Numerous organizations strongly support later start times. In 2014, the American Academy of Pediatrics issued a formal position stating that middle and high schools should start at 8:30 a.m. or later. The American Academy of Sleep Medicine made the same recommendation in 2017. The American Psychological Association (APA) has also concluded that the benefits of later start times outweigh the potential costs.

Even the RAND Corporation, an economics-focused think tank, supports later start times as their research indicates it could contribute $140 billion to the U.S. economy over a period of 15 years.


How Can Parents Help Teens Get Better Sleep?

Many parents are unaware that teens are struggling to get enough sleep and underestimate their teen’s sleeping problems. In learning how important sleep is for teenagers, many parents naturally want to know what they can do to help address this issue.

Advocate For Later Start Times

Though it may not pay immediate dividends, parents can advocate for later school start times. This can be done individually with school administrators or officials who run the school district. Parents can also work through parent-teacher organizations (PTAs) or other groups, such as the non-profit Start School Later, to lobby for changes to the school schedule in their area.

Avoid Schedule Overload

Many teens have a schedule that is totally overbooked. Between school obligations, family commitments, social activities, and other extracurriculars, teens may feel as though they have no time to sleep. The stress from this crammed scheduling can complicate sleep and emotional well-being as well. Parents can encourage teens to always make time for sleep and to try to keep their calendar balanced and reasonable.

Improve Sleep Hygiene

Many sleep disruptions can be traced back to problems with sleep hygiene. Sleep hygiene includes all aspects that affect a person’s sleep-related habits and sleep environment.

A few examples of fostering healthier sleep hygiene include setting a consistent time for going to bed and waking up each day (including weekends), reducing mental stimulation and blue light exposure from electronic devices (such as cell phones, tablets, video games, etc.) in the lead-up to bedtime, decreasing caffeine intake, and making the bedroom dark and quiet. Our comprehensive Sleep Guide for Teens goes into more detail about specific ways that teens can improve sleep hygiene.

Help Teens Get Help

There are various avenues by which teens can get help that may improve their sleep. If they have an underlying physical or mental health problem, such as obstructive sleep apnea or depression, getting treatment for that condition may make it easier for them to get better sleep.

Teens should be encouraged to talk openly about problems they are dealing with and should work with their pediatrician or another health professional, such as a psychiatrist, to address those problems.


Learn More About Teen Sleep Health