For teens, a good mood depends on good sleep

Sleeping less than eight hours — or more than 10 — makes teenagers feel worse the next day


Teenagers who don't sleep eight to 10 hours each night will be grumpy the next day.


For families with teenagers, school nights may fall into a familiar pattern. Parents urge their kids to go to bed early. But teens would rather stay up late. Maybe they have homework or want to spend time with friends. Or maybe it’s just hard to fall asleep. But a new study confirms that adolescents need eight to 10 hours of sleep at night to feel their best the next day.

As kids reach adolescence, they often face increasing workloads and responsibilities. But they are not yet adults. Their bodies and brains are still changing. As a result, “Their sleep needs are like that of a developing child,” says Rafael Pelayo. He is a sleep doctor at the Stanford Center for Sleep Sciences and Medicine in California. He was not involved in the new study.

“Adolescence is sometimes referred to as the ‘perfect storm’ of problems of sleep,” says Pelayo. On the one hand, teens need regular sleep to be mentally and physically healthy. But their internal clocks shift during this period. Their bodies want to stay awake later at night and sleep later in the morning. School still starts early, though. As a result, Pelayo estimates that 80 to 90 percent of teens do not get enough sleep.

That missed sleep has consequences. Sleep-deprived kids are more prone to mental and physical illnesses. Sleepy drivers face a heightened risk of car accidents — the top cause of teenage death. But too much sleep can have its own problems, such as leaving teens with a sour mood upon waking.

Sleep affects mood

Andrew Fuligni studies the mental health of adolescents at the University of California, Los Angeles. He wanted to understand which sleep habits help teens feel and perform their best. To find out, his team surveyed 419 students. Each was between the ages of 13 and 19. Every day for two weeks, these volunteers recorded when they fell asleep and woke up. They also rated their moods and feelings the next day, such as their happiness, anxiety and pain.

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Teens filled out this sleep form each day for two weeks. The results showed that sleeping eight to 10 hours each night was essential for them to be in a good mood the next day.Andrew Fuligni, University of California, Los Angeles

Most students reported good moods after a night of eight to 10 hours of sleep. “Too much sleep and too little sleep are both extremes,” says Pelayo. And both were linked with problems.

Within that eight-to-10-hour range, older kids seemed to need the least sleep. “A 17- or 18-year-old does not need as much sleep as a 14-year-old in order to function on a daily basis,” Fuligni found. But, he adds, “They still need a sizeable amount of sleep.”

The team published its findings August 18 in the Journal of Clinical Child and Adolescent Psychology.

Even among kids the same age, everyone needed a slightly different amount of sleep to feel good. One reason could be health issues that differ among them. For instance, in the new study, kids with anxiety and depression seemed to need more sleep to function well.

Sleep is a lot like appetite, Pelayo says. Just as people eat different amounts of food daily, sleep patterns between healthy people also may differ.

Choosing snoozing

Biologically, kids’ bodies shift toward a later schedule during the teenage years. “They become more like night owls and less like early risers,” says Fuligni. But despite the change in their internal body clocks, school start times and other schedules don’t change.

“We have set up a system that’s very difficult for many teenagers and some kids who might be at risk of mental and behavioral health problems,” he concludes.

One way to help teens get enough sleep is to have school start later. Some school districts have already done this. They’ve found that the later times let kids sleep more. They also have seen fewer car accidents, higher test scores and better graduation rates. Because of this, California lawmakers are trying to change school start times in their state. If they succeed, California middle and high schools could start no earlier than 8:30 a.m.

But until schools change their start times, teenagers have to help themselves. Pelayo suggests teens sleep for 10 hours each night for a week or two. This will help them figure out how much sleep they need to feel their best. 

Sleeping more on weekends to make up for missing sleep during the week isn’t a good idea, though. Fuligni warns that getting different amounts of sleep each night can be bad for mental health.

Pelayo agrees. “The amount of sleep you get on weekdays and weekends should be the same,” he says. We don’t starve ourselves of food on weekdays and gorge on weekends, he points out. We shouldn’t do that with sleep either.

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