How Early and Late School Start Times Affect the Mind

Raging hormones are not the only reason that many teens are grumpy in the morning. Sleep deprivation is a major concern for adolescents, especially those who have to wake up before the sun rises just so they can catch the bus on time. School start times are a hotly-debated issue around the United States, with parents, teens, and even some medical professionals advocating for starting later in the day. They have good reason for doing so; chronic sleep deprivation related to early school start times has some serious effects on adolescent behavior.

Early Start Times and Sleep Deprivation

The circadian rhythm of the body is a 24-hour cycle that involves behavioral, biochemical and physiological processes. One of the hormones that play a role in circadian rhythms is melatonin, which is secreted by the pineal gland. High levels of melatonin in the blood help induce sleep. In adolescents, melatonin levels are high in the early morning hours. While a young child might wake up at 6:00 a.m. without a problem, waking up this early is very difficult for adolescents. When adolescents consistently do not get enough sleep at night, they suffer the ill effects of sleep deprivation. In some adolescents, sleep deprivation increases the risk for obesity, sleep apnea and high blood pressure. Sleep deprivation linked to early school start times also has an effect on the mind, causing a variety of problems.

Reduced Attention Spans

Students need to pay attention to their academic work for seven to eight hours each day. In students who struggle with sleep deprivation, reduced attention levels make it difficult to concentrate on lectures, tests, and classroom assignments. Researchers from the University of Pennsylvania studied the effect of sleep deprivation on vigilant attention. Their study found that lack of sleep has several effects on attention span. It causes slowed responses and lengthy lapses in attention. Sleep deprivation also increases the amount of time it takes people to complete tasks. The results of this study appeared in the Annals of the New York Academy of the Sciences in 2008. Reduced attention span may make it difficult for adolescents to complete tests on time or hand in assignments in a timely manner. Delaying school start times by one to two hours improves attention span, which leads to improved academic performance in adolescents with normal academic abilities.

Poor Decision-Making Skills

Adolescents often struggle to make good decisions, especially when peers pressure them to do things like smoke cigarettes and drink alcohol. Sleep deprivation worsens decision-making abilities in teens, increasing their participation in risky behaviors. Researchers at the University of Texas report that moderate sleep deprivation changes the way people make decisions. The researchers studied 49 West Point cadets over a period of 48 hours. Each participant performed an information-integration task twice, with some of the participants getting a good night’s rest between tasks and some of the participants not getting any sleep between tasks. The participants who did not get any sleep between tasks showed a 2.4 percent decrease in task performance. The results of this study appeared in the November 2009 issue of Sleep. Later school start times give adolescents the sleep they need to make good decisions based on all available information.

Increased Reaction Time

Stanford University researchers have determined that a lack of sleep affects reaction time just as much as consuming alcohol does. These researchers conducted a study to determine the effect of sleep apnea on reaction times. People with sleep apnea experience short periods of interrupted breathing at night, which disrupts their sleep and leaves them feeling tired the following day. Sleep apnea also prevents the body from entering the deepest stages of sleep.

The study included 113 people with mild to moderate sleep apnea and 80 volunteers without sleep apnea. The volunteers without sleep apnea got three consecutive nights of good sleep prior to participating in the study. During the study, the people without sleep apnea took reaction time tests sober to get an idea of their baseline performance. Then they drank orange juice and vodka, performing the test three additional times at blood alcohol levels of 0.057 percent, 0.08 percent and 0.083 percent. The sleep apnea patients performed far worse than the volunteers did at a blood alcohol concentration of 0.057 percent. They also scored just as poorly as those with a blood alcohol concentration of 0.08 percent, which is the legal blood alcohol limit for all 50 states.

Teens who participate in sports or other activities that require quick reaction times may find themselves performing poorly when they have to get up very early for school. Teen drivers are especially at risk for serious issues caused by sleep deprivation. Slowed reaction times make it difficult to brake in time to avoid a stopped vehicle or to change lanes quickly if there is a sudden obstacle in the road. This increases the risk of auto accidents involving teens. Some schools that have experimented with later start times report a decrease in the number of accidents involving teen drivers in their communities.

Additional Effects

Reduced attention span, poor decision-making skills and slowed reaction times are not the only effects of sleep deprivation on adolescents. The American Academy of Sleep Medicine says that sleep deprivation also causes lack of motivation, irritability, lack of concentration, restlessness, distractibility, increased errors, anxiety, forgetfulness and symptoms of depression. If a teen exhibits the symptoms of depression, it may be worth tracking his or her sleep pattern to determine if sleep deprivation is responsible for irritability, anxiety or other related symptoms.

Later school start times have clear benefits for students. Because not getting enough sleep affects attention span and decision-making skills, students who start class later perform better in school. These students also perform better in sports and other extracurricular activities. Because many people do not understand the connection between sleep deprivation and poor performance, educating others is one of the only ways to convince educators and administrators to delay school start times for the good of their students.

About Leigh Ann Morgan

I write about all sorts of things but ever since I completely got rid of my constant neck pain by finding the perfect pillow, I've started to learn as much as I can about sleep quality and sleep disorders.


  1. It’s interesting that preschoolers can wake up easily at 6:00. They would have 30 minutes to get dressed, eat breakfast and get to school. Factor in siblings and it would be impossible to get ready for school without having to wake up earlier!!

    It is negligent not to work for change to a later school time. Local efforts to change inevitably spark raging controversy. Politics, money and misunderstanding often override the best interests of students, teachers and communities. 

    We believe collective action on a national scale is the only way to ensure that all public schools can set hours compatible with health, safety, equity, and learning. You can take action and sign our petition here:

    Maribel Ibrahim

  2. Dolores Skowronek says:

    The start time at my son’s high school is among the earliest in the nation. His school starts at 7:10 a.m. and I can tell you that it absolutely impacts his mood and ability to learn. I’m glad to see this issue getting some national attention. School districts need to recognize the research and do what’s best for the health and education of our children. I am proud to say that I signed a national petition for later start times, I hope others will too. Here is the link:

  3. icecream says:

    Hi I was wondering if u could tell us some health issues caused by coming to school early because I have to write an essay and our teacher told us to research first. I have searched everywhere but its not there..please help me…

  4. Matthew Proctor says:

    Leigh Ann wrote another article about the health issues involved in starting school early. You can find it here: Early Vs Late School Start Times: How They Affect Students Physically. Hope that helps! Good luck on the paper.