Later Bedtimes Linked to Lower GPAs for Teens

Adolescent sleep patterns shown to be linked to academic performance and emotional health

/ Author:  / Reviewed by: Robert Carlson, M.D Beth Bolt, RPh

(RxWiki News) Between finding time to do homework, extracurricular activities and hanging out with friends, it can be hard for teens to get enough sleep. But if they don't, it might negatively affect their performance in school and lead to emotional problems.

A recent study found that having a later bedtime during the school year was linked to less total sleep, more emotional problems and a lower GPA for students.

The researchers also found that late bedtimes during the summer had a negative effect on emotional outcomes.

"Make sure your teen gets nine hours of sleep daily."

This study was led by Allison G. Harvey, PhD, of the Department of Psychology at the University of California, Berkeley. The research team examined the sleep patterns of teens and looked to see if these patterns were connected to emotional outcomes or academic performance.

Data was analyzed from 2,700 students between grades 7-12 in the National Longitudinal Study of Adolescent Health Study (Add Health). Data was collected for Add Health in three waves during 1995, 1996 and 2001-2002.

Students were asked, “During the school year, what time do you usually go to bed on the week nights?” Based on their responses, participants were split into three groups: the late group (after 11:15 pm), the middle group (between 10:15-11 pm) and the reference group (after 7 and before 10:15 pm).

Students were asked the same question about their summertime sleep schedules. Based on their responses, participants were split into three groups: late group (after 1:30 am), middle group (between 11:45 pm and 1 am) and reference group (before 11:45 pm).

Students were also asked about the total amount of sleep they got. Participants were separated into two groups based on the current recommendation that teens should get nine hours of sleep: adequate (nine hours or more) or inadequate (less than nine hours).

The researchers used the cumulative GPA listed on each student’s transcript as a measure of academic performance.

Emotional distress was measured by asking students about whether they felt sad, depressed, were bothered by things that did not normally bother them, could not shake the blues for a lot of time over the previous week and cried more than once a week over the previous year. Students who reported two or more of these feelings were considered to be distressed.

Several factors were taken into account that could have influenced academic performance and emotional outcomes. These factors included age, gender, race/ethnicity, welfare status and pubertal status (had they reached puberty).

The researchers found that having a later bedtime was linked to a shorter amount of total sleep.

Late school year bedtimes in Wave I (1995) were linked to emotional distress and worse academic performance (lower GPA) six to eight years later.

Late summertime bedtime in Wave II (1996) was linked to more emotional distress at Wave III (2001-2002).

The researchers also found that total sleep time was not connected with changes in emotional distress or academic performance.

Based on their data, the study authors noted that roughly one-third of teens who were unable to get to sleep before 11:30 pm during the school year were likely to perform worse in school than students who got to sleep before 11:30 pm.

They concluded that more attention is needed to understand the negative effects that poor sleep can have on teenagers' health and development.

William Kohler, MD, the medical director of the Florida Sleep Institute, told dailyRX news that, ”Previous studies have noted significant behavioral, cognitive and weight changes with insufficient sleep. Teenagers are particularly prone to delayed sleep phase syndrome with inability to get to sleep until late." 
“A relatively rigid schedule day in and day out varying no more than an hour has been found to be beneficial,” said Dr. Kohler, not associated with the study.

This study was published on November 10 in the Journal of Adolescent Health

The study authors reported no competing interests.

This study was funded with a series of fellowship awards and grants from the National Science Foundation and the National Institute of Child Health and Human Development.

Review Date: 
November 12, 2013
Last Updated:
November 14, 2013