What time should you wake up? Probably not 5am.

Subscribe to enjoy similar stories. As we emerge from the drowsy holidays with aspirations of being fitter and more productive, one social-media trend jumps out: How about waking up everyday at 5 a.m.? It’s true, some of the world’s top CEOs and elite athletes swear by early rising. But sleep experts say it can set you up for failure.

“The trend of waking up at 5 a.m. is the second stupidest thing I’ve heard in a long time," says Michael Breus, a sleep doctor in Hermosa Beach, Calif. (The first? Taping your mouth shut at night.) “If you’re a night owl who wants to get stuff done and you try waking up at 5 a.m., you’ll last a week, and you’ll become self-defeated and depressed." We’re a sleep-deprived nation.

In a Gallup poll last year, 57% of Americans reported they would feel better if they got more sleep but said their stress prevented that. Around 20% of respondents said they got five or less hours a night. A decade ago, it was 14%, and back in 1942 it was just 3%.

Many people get less than the recommended seven to nine hours of nightly shut-eye because they want to squeeze in a workout, have some alone time or get more done. Some go-getters get up even earlier than 5 a.m. So what time should you wake up? That depends on a few factors based on your habits, age and genetics.

Lark, bear or owl? “Sleep is thought of as this thing that needs to be subjugated and bludgeoned into submission when really it needs to be embraced like a teddy bear," says Russell Foster, a professor of circadian neuroscience at the University of Oxford. Studies have shown sleep deprivation can lead to heart problems, immune suppression, depression and an increased risk of dementia. Foster isn’t a fan of the 5 a.m.