How Do Later School Start Times Affect Sleep?


Written by Dr. Michael Breus

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Weekday mornings can be a challenge for teenagers and their parents. Instead of waking up early in the morning to get to class, many teens would rather resist the call of their alarm and stay asleep in bed. Since sleep is vital to the developing minds and bodies of young people, it’s natural for them to crave more of it.

Experts believe that teens need between 8 and 10 hours of sleep every night. However, nearly 60% of middle schoolers and more than 70% of high schoolers are not getting enough sleep.

Insufficient sleep can translate into poor academic performance. It can also increase the risk of long-term health problems such as obesity, diabetes, and mental health issues.

Early school start times may be part of the problem. Evidence shows that starting school later increases teenagers’ sleep time and improves safety and academic performance, and expert groups support later start times for middle schools and high schools. We discuss the current state of school start times in the U.S., the many impacts of early start times, and the pros and cons of shifting school schedules to begin later.

What Time Do Schools Start Now?

According to recent data, the average public high school in the U.S. starts classes at 8 a.m. Health expert recommendations for school start times are beginning to reflect the serious need for sleep among teens. But actual school schedules across the U.S. do not always match the latest guidelines.

In 2014, the American Academy of Pediatrics recommended that middle schools and high schools should start at 8:30 a.m. or later. But according to a CDC study from the same year, most high schools and middle schools in the U.S. began before 8:30 a.m. By 2018, school start times remained largely unchanged, with over 40% of all U.S. public high schools starting before 8 a.m.

Start times can vary significantly depending on the school. Smaller high schools tend to have later start times than larger schools, and rural schools tend to start later than those in cities and suburbs. Start times also differ from state to state. Average high school start times range from 7:30 a.m. in Louisiana to 8:41 a.m. in the District of Columbia.

Policy can be slow to reflect changes in public health recommendations. But some state legislatures are beginning to heed the advice of medical experts. In 2019, California passed a bill to ensure that first period classes would start no earlier than 8:30 a.m. for all high school students and 8 a.m. for all middle school students.

How Do School Start Times Impact Students?

Children and teenagers need more sleep than adults. Yet modern life places many demands on school-aged kids that can cut into their sleep time, such as daily homework assignments, sports and other extracurricular activities, part-time jobs, and social obligations.

On top of these demands, early school start times contribute to higher rates of sleep loss among pre-teens and teens. Sleep loss can have a wide range of effects for young people, both inside and outside of school.

School Performance

Requiring students to start class early in the morning while running a sleep debt can hurt their academic performance.

Regularly losing sleep impairs students’ memory, organization skills, and ability to manage complex tasks, all of which are crucial for learning. Moreover, sleep loss makes students tired. In one poll, nearly 3 in 10 students reported falling asleep at school once a week or more.

Chronic sleep loss can also lead to:

  • Trouble paying attention and staying focused
  • Loss of creativity
  • Inability to think abstractly
  • Poor grades
  • Lower attendance rates
  • Higher dropout rates

Additionally, not getting enough sleep can impact a student’s emotional state, making it more difficult to positively contribute while in class. Sleep deprived adolescents are more likely to experience:

  • Reduced motivation
  • Increased sensitivity to stress
  • Reduced impulse control
  • Difficulty interpreting social cues

Outside of School

The effects of sleep loss go beyond grades. Poor-quality and insufficient sleep are linked to a wide array of health consequences, behavioral issues, and mental health risks for pre-teens and teens.

  • Chronic disorders: Not getting enough sleep on a regular basis may contribute to obesity, high cholesterol, type 2 diabetes, and high blood pressure, among other conditions.
  • Mental health issues: Chronic sleep loss in adolescents can increase their risk of depression and anxiety and make it harder to regulate emotions.
  • Driving accidents: Drowsy driving is a major risk for drivers of all ages. Sleep-deprived teens are more likely to get into a collision or other traffic accident.
  • Stimulant use: Adolescents who do not get enough sleep are more likely to overuse caffeine as well as prescription stimulants.
  • Risk-taking: Teens who experience sleep loss may be prone to partaking in risky practices such as alcohol and tobacco use, drug abuse, unsafe driving, high-risk sexual activity, and hostile behavior.
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Should School Start Later?

Many major health organizations, such as the Centers for Disease Control and Prevention and the National Sleep Foundation, recommend that middle and high schools start later in the morning. Despite this consensus among health experts, actual school start times have been slow to change.

Current early school start times can be especially detrimental to teenagers because of the unique sleep-wake cycle of adolescence. As children enter puberty, their internal sleep clock or circadian rhythm begins to shift, causing them to fall asleep later in the evening. But early school schedules prevent pre-teens and teens from waking up later to make up for their later bedtimes.

Shifting middle and high school start times later in the morning can help correct this problem and may convey other benefits as well.

What Are the Benefits of Starting School Later?

Because teenagers have a natural tendency to go to sleep later, delaying school start times allows teenagers to wake up later in the morning and sleep during the best hours for their bodies. Research shows that later school start times lead to increased weeknight sleep for the average middle school and high school student.

Getting the appropriate amount of sleep has far-reaching benefits for students, from improving academic engagement to improved physical and mental health. On the academic side, later school start times are associated with:

  • Better class attendance
  • Reduced tardiness
  • Higher grades
  • Staying awake in class
  • Less drowsiness while doing homework

Starting classes later may have benefits outside of school as well. Later school start times are also associated with:

  • Fewer car accidents
  • Waking up earlier on weekends
  • Decreases in depression symptoms

Later start times may not be beneficial for all ages and grade levels. Some research suggests that earlier school start times may not lead to sleep loss or daytime sleepiness in elementary school students.

Are There Drawbacks to Later Start Times?

Shifting school start times later has clear benefits for improving sleep but may create scheduling complications.

  • Conflicting schedules: For parents working a traditional 9 a.m. to 5 p.m. job, early school start times fit neatly into the workday schedule. Later start times may make it more difficult for parents and kids to coordinate their morning schedules.
  • Transportation logistics: Start times are usually staggered for elementary, middle, and high schools to make planning school bus transportation easier. Later school start times would complicate school bus logistics and require careful planning to overcome.
  • Less time after school: A later start time also means a later end time. With school ending later in the afternoon, students may have less time for other activities on weekdays including homework, tutoring, sports, part-time jobs, spending time with friends, and hobbies.

School start times shape the morning routine and daily schedule of nearly every student, parent, caregiver, and teacher. Changing school start times involves navigating logistical challenges that aren’t always easy to overcome.

About The Author

Dr. Michael Breus

Clinical Psychologist, Sleep Medicine Expert

Michael Breus, Ph.D is a Diplomate of the American Board of Sleep Medicine and a Fellow of The American Academy of Sleep Medicine and one of only 168 psychologists to pass the Sleep Medical Specialty Board without going to medical school. He holds a BA in Psychology from Skidmore College, and PhD in Clinical Psychology from The University of Georgia. Dr. Breus has been in private practice as a sleep doctor for nearly 25 years. Dr. Breus is a sought after lecturer and his knowledge is shared daily in major national media worldwide including Today, Dr. Oz, Oprah, and for fourteen years as the sleep expert on WebMD. Dr. Breus is also the bestselling author of The Power of When, The Sleep Doctor’s Diet Plan, Good Night!, and Energize!

  • POSITION: Combination Sleeper
  • TEMPERATURE: Hot Sleeper

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