After puberty, adolescents tend to fall asleep and wake up later than they did before puberty. This shift in sleeping pattern has been attributed to environmental changes, including peer culture, academic demands, and extracurricular activities. But since adolescent sleep patterns are consistent across cultures, some researchers have proposed that it is biology—not environment—that causes shifts in adolescents’ sleeping patterns.

A new study in the November issue of the journal Sleep examined the brain activity of sleep-deprived children and adolescents, and found that the biological processes that trigger sleepiness occur later in adolescents than they do in children.

About the Study

This study included seven pre- or early-pubescent children (5 girls, 2 boys; average age=12) and six mature adolescents (4 girls, 2 boys; average age=14) who were participating in a sleep study at the Brown Medical School sleep lab. After 10 consecutive nights of 10 hours of sleep at home in dark, quiet rooms, the participants visited the sleep lab. During the visit, the researchers measured the brain activity of the participants using electroencephalography (EEG) during a “baseline” night of 10 hours of sleep, a 36-hour period of sleep deprivation, and an 11-hour, 40-minute “recovery” night of sleep.

The EEGs indicated that, compared with the children, the adolescents experienced slower rises in “sleep pressure,” which is the biological trigger that causes sleepiness. When sleep pressure rises faster, as it does in children, sleep comes on earlier. When it rises slower, the “pressure” to sleep occurs later in the evening.

This study was limited because it was small, consisting of only 13 participants. Results from a larger study would be more reliable.

How Does This Affect You?

These findings indicate that biology may be the reason teenagers fall asleep and wake up later than younger children. The authors of the study propose that this shift in sleeping pattern may be the body’s way of preparing adolescents for adulthood, when it is often necessary to perform tasks while sleep deprived.

If you are the parent of a teenager, it is comforting to know that rebellion may not be the reason your child stays up late. Rather, there is apparently a hard-wired biological process driving your teenager’s insistence on late nights. Changes in sleep patterns during and after puberty are completely normal, and in all probability, your child will be able to go to sleep and wake up with the rest of humanity again one day.