Why You Feel More Tired When You Sleep Late

It all depends on which stage of sleep you wake up in, says a sleep expert. 

In a typical night, you cycle through five stages of sleep several times, explains Michael Breus, PhD, a Los Angeles–based psychologist and sleep specialist. Sleeping longer than normal means you may wake up during one of the deeper stages, when your body is still producing high volumes of the sleep-inducing hormone melatonin. This can leave you feeling groggy.

“If you wake up at a stage-three or stage-four sleep,” Breus says, “you have that logy, exhausted feeling, which we often call ‘sleep drunkenness.’”

And it’s more than just a feeling, he adds. It can impair your judgment and clarity for up to four hours. You can avoid this condition, known as sleep inertia, by getting up at the same time every morning, no matter when you went to bed.

“Consistency is key here,” Breus says. “The more consistently you wake at the same time, even on weekends, the more likely you are to wake up at a lighter stage of sleep.”

This practice eventually trains your body to become tired at the same time every night. Then it’s easier to go to bed earlier — and at a consistent hour. Soon you’re getting your optimal amount of sleep routinely and not confusing your biological rhythms by sleeping in.