Skip to main content

Verified by Psychology Today


Do Later School Start Times Really Help High School Students?

Evidence supports later school starts for high school students.

It is now well established that teenagers have a tendency toward later bedtimes and rise times. Most high schools in the U.S. have early-morning start times. For many high school students, this results in a conflict between their sleep needs and the requirements of their school schedules. So, do later school times really help high school students? Based on accumulating evidence, the answer is unequivocally yes. Increasing numbers of studies conducted in various parts of the country show that a change in the start time of the school day can make a significant positive change in the lives of students.

Many high school students live in what Dr. Mary Carskadon calls a continuous state of jet lag. Carskadon has been involved in some of the most important research on the sleep need of teens. This research indicates that adolescents need about 8.5 to 9.5 hours of sleep a night. If you know any teenagers today, you realize that very few are getting anywhere near this amount. Starting school later could help students get more sleep. Starting classes later, closer to when their biological clocks are most ready for learning, could make a real difference in how much knowledge a teen acquires at school.

Several studies have been conducted over the past 15 years that indicate how a later start time for school can affect students. Most have been carried out in public schools although some research is happening at private schools as well.

Changes made in school start times in several locations in Minnesota in the 1990s showed early positive results. Keeping the length of the school day the same but changing the start of the school day from 7:15 a.m. to 8:40 a.m. or from 7:25 a.m. to 8:30 a.m. resulted in improved functioning for both urban and suburban students. Urban students had better attendance, decreased tardiness and fewer visits to the school nurse. Suburban students tended to keep their regular bedtimes and so added about an hour of sleep per night and were able to get more homework done during the day because of increased alertness and efficiency. In Massachusetts, a change in middle-school start times for younger teens also proved beneficial. Students at a school with an 8:37 a.m. start time slept about one hour more, had less difficulty staying awake in school, and had better grades than students at a school with a 7:15 a.m. start time. A recent study at a private Rhode Island high school showed that shifting the start time from 8 a.m. to 8:30 a.m. increased the number of students getting 8 hours of sleep a night from 16% to 55%, improved attendance, and resulted in fewer visits by students to the health center. Mood improvements were also noted among the students. Perhaps most dramatic of all were results from a school district in Fayette County, Kentucky. In the 1990s, after a change in start time from 7:30 a.m. to 8:30 a.m., a decrease was found in car accident rates for 16- to 18-year-olds in the Fayette County school district, while rates actually increased in the rest of the state for 17-18-year-olds. Given the danger posed to young people from car accidents, this is a strong reason in itself to change school start times. A great source for information on students and sleep can be found at the National Sleep Foundation website.

There are, of course, some potential negative effects associated with later start times and longer sleep periods. It can be disruptive to parents' work schedules, result in shortened times for after-school activities such as sports and clubs, cause students to get home later in the day, and may also impact hours available for after school jobs. These challenges may be more difficult to accommodate in some settings than others. For example, parents in suburban schools may have greater difficulty coping with the changes in transportation and work schedules than those in an urban setting. But on the whole, the benefits outweigh the costs of making this change. By simply adjusting school start times, far fewer students will be sleepless in America.

More from John Cline Ph.D.
More from Psychology Today