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You Can’t Sleep Late as an Adult Because Your Brain Is All Grown Up

Remember the good old days — aka, your teens — when you could go to bed at midnight and sleep until three in the afternoon? Now, remember the last time you went to sleep at 4 a.m. and still woke up three goddamn hours later? Needless to say, sleep in adulthood blows. But what exactly is it about our no-longer-teenage selves that keeps us from snoozing the day away? According to Terry Cralle, certified clinical sleep educator and author of Sleeping Your Way to the Top: How to Get the Sleep You Need to Succeed, it’s primarily because we’re no longer sleep-deprived.

“Teenagers oftentimes experience what’s known as delayed sleep phase syndrome (DSPS), which essentially delays their sleep schedule by two or more hours,” Cralle explains. While the cause of this phenomenon is unclear, scientists think DSPS may be an exaggerated reaction to the circadian rhythm shift that teenagers experience after puberty, which already pushes their sleep schedule back by about two hours.

“On top of that, teenagers are usually incredibly sleep-deprived, since they need 9.25 hours of sleep per night. They don’t get anywhere near that much sleep, because delayed sleep phase syndrome keeps them up late into the night, then school starts ridiculously early.” As a result, teenagers accumulate a ton of sleep debt during the week, which they make up for by sleeping late into the afternoon on weekends.

There’s more research to back this up: One 2009 study found that teenagers do indeed experience a delayed sleep phase — their bodies perform better when staying up later and sleeping in longer. Research like this influenced both the American Academy of Pediatrics and the Centers for Disease Control and Prevention to not only perform their own research on the matter, but to also recommend that schools start no earlier than 8:30 a.m. They note that earlier start times are linked to poor academic performance, obesity and depression (all of which may relate to sleep deprivation).

On the flip side, our adult selves have grown out of this phase, and we get more sleep as a result: “For the most part, you’re going to bed earlier than you were as a teenager, and you’re getting enough sleep as a result,” Cralle says. “So even if you stay up until 3 a.m. every once in a while, you’ll still wake up whenever you normally would because you’re not sleeping off a debt.”

So while you might be upset — okay, fuming — that your body only lets you sleep for three hours after a late night out, be glad it’s only doing so because you’re generally doing better than your teenage self.