by Mary A. Carskadon
Alpert Medical School of Brown University, Providence, RI USA
Mary A Carskadon PhD is Professor of Psychiatry and Human Behavior at Brown University, is the doyenne of sleep and circadian rhythm research in children and adolescents, and an engaged advocate for improving their sleep.
Sleep in adolescents has been a significant concern in many countries around the globe. Scientists and physicians have determined that the optimal sleep need for teens is roughly 9 hours each night, though the range of 8 to 10 hours is thought to be a good time frame for most adolescents. With that in mind, reports of sleep duration in mid- to late adolescence average about 7 hours a night; in other words, two hours less than needed, on average. Across a school week, that adds up to about 10 hours of lost sleep. To help make up for this deficit, many young people will sleep much longer on weekends, staying up later and sleeping in later in the mornings.
Two biological factors carry much of the challenge to teenagers’ sleeping. First is the way their daily biological clock shifts as they pass into puberty; it shifts to a later time that makes falling asleep as they did when younger very difficult if not impossible. Second, at the same time, the system that builds up pressure to fall asleep the longer we are awake becomes weaker, again making it hard to fall asleep. These biological factors would be just fine if teens were “allowed” to sleep on their natural schedule of going to bed and waking up late; they would still get plenty of sleep.
The real problem comes when these youngsters are required to wake early in the morning to get ready for and go to school. Between later bedtime and earlier rising time, sleep gets squeezed out of their school nights. Indeed, this pattern is almost like jet lag without leaving home! Their body thinks they should be living 2 or 3 hours westward of where the school schedules have them. This is called social jet lag.
The burdens and risks of social jet-lag are at least three-fold: (a) personal daytime experience – falling asleep in class, depressed mood, anxiety, overeating at night; (b) family stresses and alienation; and (c) poor health – lowered immune response, weight gain, diabetes.
The problem of insufficient sleep in teenagers, tied to school schedules, is most acute in the United States and constitutes a significant public health concern. The Centers for Disease Control and Prevention, and the American Academy of Pediatrics recommend that school days for year 5-12 students (middle and high school) not start until 8:30 AM or later. Even so, some teens will continue to suffer because the change in their sleep system and body clocks still cannot adjust. Thus, teen sleep is often both too late and too little.