关注青少年睡眠不足问题

RENEE MONTAGNE, host: This is MORNING EDITION from NPR News. Good morning, I'm Renee Montagne.
Today in Your Health, we look at a chronic problem among teenagers - a lack of sleep. Research has shown that depression rates in teens go up as their hours of sleep go down. Reporter Michelle Trudeau says there are ways to deal with the sleep shortage that most teens accrue during the school week.

MICHELLE TRUDEAU: Your high schooler's chronically tired, right? Stays up late every night - surveys say close to midnight - finishing homework, texting friends, screen time, doing whatever teenagers do. And then has to get up early - typically 6, 6:30 - for school the next morning. Happens five days a week, with your teen getting more and more tired. Then comes the weekend.

Dr. HELENE EMSELLEM (Researcher, George Washington University): Every parent of a teenager knows that if you try to get them up in the morning on the weekends, they are tired, grouchy(adj. 爱抱怨的;不高兴的), irritable and not the charming individuals that they're capable of being, because they're so exhausted.

TRUDEAU: That's sleep expert Helene Emsellem, a neurologist(神经专家)at George Washington University who's literally written the book on teenage sleep issues. She says the typical high school senior gets about seven hours of sleep on school nights. And yet...

Dr. EMSELLEM: Most studies that have been done have shown a fairly consistent 9 1/4 hours sleep requirement. So there's a huge gap between what they're getting on an average school night and what they require.

TRUDEAU: As teen progress through puberty(n.青春期), uNPRecedented growth in body and brain requires lots of sleep. And there's something else changing: The very brain chemical that makes one feel sleepy – melatonin(褪黑激素)- is released later and later in the evening as teens get older.
Because of this shift, says sleep researcher Stephanie Crowley from Rush University, teenagers just don't feel sleepy till later at night.

Dr. STEPHANIE CROWLEY (Behavioral Sciences, Rush University): So compared to say a 10-year-old, a 16- or 17-year-old might be able to stay awake later compared to a 10-year-old that will likely fall asleep on the couch watching TV.

TRUDEAU: Result - by the end of each school week your average teenager has accrued as much as five to ten hours of sleep debt, which brings us back to the weekends.

Dr. CROWLEY: What the majority of adolescents do is they will try and recover their sleep on the weekends. What usually will happen is they'll stay up late to socialize with friends and then sleep-in in the morning.

TRUDEAU: But this pattern makes things worse for the teen, not better. Again, Helene Emsellem.

Dr. EMSELLEM: So even if you catch-up by sleeping in late on your weekend mornings, by doing so, it makes it harder for you to fall asleep by 10 or 10:30 on Sunday night. And you start all over again, sleep restricted.

TRUDEAU: But Emsellem offers some suggestions for the weekends, based on her research in the lab - and raising three daughters.

Dr. EMSELLEM: I honestly, as a parent myself, feel like a criminal if I ask them to get up at 7:30 or 8 o'clock in the morning. But I do try to get them to get up by 9. And I encourage them to get up and get some activity and some light exposure in the morning.

TRUDEAU: Emsellem calls light a drug that promotes wakefulness in the morning, in the same way that darkness can promote sleep.

Dr. EMSELLEM: In the evening, after nine o'clock at night, I try to have them dim down the lights, minimize light exposure.

TRUDEAU: Literally turn off some lights in the house. And make a transition to sleep, like take a warm shower.
And there are some don'ts.

Dr. EMSELLEM: Don't run, run, do homework, talk to everybody, text message everybody, leap in bed, turn out the lights and expect yourself to fall asleep.

TRUDEAU: And when teens can't fall asleep, getting frustrated just lying there...

Dr. EMSELLEM: This is where some of their electronics used really carefully can be helpful - listening to a soothing(soothe vt.安慰，使平静)playlist with the lights out, listening to a book but setting a timer on it for 30 minutes.
And two more tips: no caffeine, no chocolate after 2 p.m. And try to get an early afternoon nap, both on the weekends and during the week.

Dr. EMSELLEM: I encourage teens if they have a break during the day to use that study hall or break, if they're permitted to, for a 20 minute nap, particularly by the way if they have a test in the afternoon. Studies have shown they'll do better on their test with a nap midday.

TRUDEAU: And they will have more energy and concentration to power through their homework later in the evening.

For NPR News, I'm Michelle Trudeau.

MONTAGNE: If you have questions on teens and sleep you can submit them to NPR.org/health. We'll ask a panel of sleep experts and post their answers online later this week.