As children enter adolescence, they change physically, emotionally and biologically. These changes manifest in their bodies, their health, and their social/academic functioning. One major change is in the timing of the sleep/wake cycle. The inability of teens to alter their daily schedules to adapt to their bodies' needs has been identified as a significant source of physical and emotional stress.
Studies have shown that most teenagers are chronically sleep-deprived, despite their efforts to catch up by sleeping extra late on weekends. Their internal clocks are accurately telling them to stay up later and sleep later. But middle schools and high schools tend to start quite early and often teens have to awaken between 5-6 am to get to school on time. Lack of sleep has been shown to contribute to depression, inattention, poor behavior, and academic failure. Teenagers ideally require nine hours of sleep per night. Few are able to get it.
The percentage of students who slept at least 8 hours rose from 16% to half.
Sleep/wake cycles change in adolescence. Their bodies tell them to fall sleep later, and, similarly their systems are not ready to awaken as early as they used to in childhood. Biologically, the timing of the secretion of melatonin by the pineal gland changes. Melatonin levels are typically very low during the daytime, rise before sleep time, and decrease again when it is time to awaken. In adolescence, these peaks and valleys are shifted towards a delayed sleep and wake time.
But what if school started later? A recent study, published in the Archives of Pediatrics and Adolescent Medicine, looked at the impact of changing the time school starts had on teens. The idea was to start later to allow high schoolers to sleep longer.
At the small private school in the study, where students are primarily boarders, the start of the school day was delayed by 30 minutes. There were no changes in the lights-out schedule. The students completed surveys at the beginning and end of the two- month study period. The investigators monitored the students' sleep habits, daytime fatigue, mood, and health. The teachers reported on class attendance, tardiness, and behavior. Two hundred and twenty-five students participated in the study.
The results, both objectively and subjectively, were impressive, particularly since the start of the day was only delayed by 30 minutes. The students slept an average of 45 more minutes on school nights and the number of students sleeping less than 7 hours per night decreased from one–third of the population to less than one-tenth. The percentage of students who slept at least 8 hours rose from 16% to half. Even so, the percentage of students who were getting the recommended nine hours per night was still quite low, at 11%.
The students reported less depression, less sleepiness, more positive feelings about themselves. The teachers noted an improvement in classroom attention and the parents described their children as being easier to live with.
This study adds to the growing body of literature on the impact of sleep and adolescent mental and physical health and academic and social functioning. In 1997, an entire school district in Minneapolis with 49,000 students from K-12 shifted the start of high school and middle school by 30 minutes later. The students reported less depression, less sleepiness, more positive feelings about themselves. The teachers noted an improvement in classroom attention and the parents described their children as being easier to live with.
An editorial that accompanies the recent study describes the difficulties of changing in the start time of a school. From school system bus schedules, to parental employment, to student after-school activities, the start times of school influence many schedules. School start changes are contentious issues. However, this recent study, along with those that preceded it suggests that successful social, emotional, and academic functioning are not just matters of importance to individual teens, but also to society as a whole. Information about the biological rhythms of the adolescent system should be used to improve the opportunities for adolescents to grow into a generation of healthy, well-functioning adults.