Sleep and the Teenage Brain
A Many parents believe that their teenage children stay up late and sleep until noon because they are lazy. Research suggests that there is a biological reason. During adolescence the body clock moves later. The brain releases a hormone called melatonin, which makes people feel sleepy, about one or two hours later in the evening than it does in a younger child or an adult. A teenager may therefore feel wide awake at ten o'clock at night and may not be ready to sleep until close to midnight. Doctors recommend that teenagers should sleep for between eight and ten hours each night, which is more than most adults need.
B Unfortunately, the school day does not follow the same pattern. In many countries lessons begin before eight in the morning, so a student must wake at six, at a time when the body still expects to be asleep. If the same student goes to bed at midnight, the result is only six hours of sleep. This shortage builds up over the week as sleep debt. At the weekend teenagers often sleep until late in the morning to recover, but this moves the body clock later still, and on Monday morning it is even harder to get up. Researchers sometimes compare the effect to flying across several time zones every weekend.
C The costs of too little sleep are well documented. A tired student finds it harder to concentrate, to take in new information and to control strong feelings. Sleep is also the time when the brain sorts and stores what was learned during the day, so a student who does not sleep enough may remember less of the lesson. Studies of young drivers have found that those who sleep for fewer hours are more likely to have an accident. Doctors also warn that long periods of poor sleep are linked to anxiety and low mood.
D A number of schools in several countries have tried a later start to the day, usually by thirty minutes to an hour. Teachers in these schools report that students arrive in a calmer state and are more alert in the first lessons, and some schools recorded a fall in the number of late arrivals and absences. A few studies found small gains in test scores. However, researchers point out that the results differ from one school to another and that it is too early to say whether the improvements last for many years.
E Changing the school timetable is not easy. Many schools rely on the same buses to carry students at different times, so a later start for one group changes the bus schedule of the others. Sports teams that train after lessons may have to finish in the dark, and parents who start work early would have to make new arrangements for their children. Some councils are also concerned about the cost of making these changes, and these problems have prevented many schools from taking action.
F Meanwhile, families can do a good deal without waiting for the timetable to change. Light from screens in the evening can delay the release of melatonin, so doctors advise teenagers to put their phones away an hour before bed. A regular time for going to bed and getting up, including at weekends, helps the body clock. Drinks that contain caffeine should be avoided in the afternoon and evening. Some schools have started to include lessons about sleep in the health curriculum so that students can understand why it matters.