After a week of sleep deprivation, I always look forward to sleeping in on Saturday—but more often than not, I’m just trading one form of out-of-it for another. I wake up at noon with a foggy brain that seems to work in slow motion. I shouldn’t be surprised; my mom warned me as a kid that you can get tired from sleeping too much, but I figured that was her way of combating chronic adolescent sloth. Is it actually excessive sleep that’s causing the fog, or is it something else?
When catching up on sleep only seems to make you more tired, there could be a few different things going on. One common source of this “sleep inertia” is that your brain is confused because you’ve disrupted your circadian rhythm, says W. Christopher Winter, president of Charlottesville Neurology and Sleep Medicine and author of The Sleep Solution. When we wake up at the same time every day, our bodies learn to become alert around that time, he explains. If we sleep in instead, we don’t get that cue to fully wake up, especially if we’ve also stayed up later than usual. It’s the same reason many people feel worse after a nap or get jet-lagged.
“Your body sleeps in cycles,” Winter explains. “If you’re on a rhythm, you get up, you exercise, you’re at work by 8, then you go to bed after Colbert. Then on the weekends, when you go out on Friday night with your friends and sleep until noon, your brain all of a sudden is not sure what’s going on. Your brain sees light for the first time at noon, it thinks the sun’s come up, it’s thinking your lunch is your breakfast… your brain is really not sure what it’s supposed to be doing.”
Adding to the confusion, departing from your routine can lead you to wake up during the wrong sleep stage. Typically, we go through five 90-minute sleep cycles per night, each of which contains four sleep stages, explains Sara Nowakowski, clinical psychologist and assistant professor at the University of Texas Medical Branch. If your circadian rhythm is thrown off, you might wake up in the middle of a cycle rather than after you’ve completed one, which will feel disorienting.
One way to sleep in without confusing your brain is to wake up when you normally do, get outside, and have breakfast before going back to sleep, Winter tells me. “If you go back to sleep, your body understands it’s more of a nap and not a continuation of your sleep schedule,” he explains. You could also just aim to sleep only an hour later than usual, which shouldn’t throw you off too much, says Dawn Dore-Stites, assistant professor at the Pediatrics and Sleep Disorder Center at Michigan Medicine.
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If you’re tired after sleeping a lot and it’s not a departure from your usual sleep schedule, it’s possible that you actually have a health condition that’s making you sleep a lot and making you tired, Winter adds. The American Academy of Sleep Medicine and Sleep Research Society recommends adults get seven to nine hours of sleep a night, so sleeping more than that regularly may indicate hypersomnia, or “excessive daytime sleepiness that is usually not relieved by a nap,” Nowakowski says. It could also point toward depression, sleep apnea, or narcolepsy.
Don’t panic though. Much of time—especially if it hasn’t been a long-term issue—it’s less serious. The tired feeling you get after sleeping a lot could also be a residual effect of the sleep deprivation that caused you to sleep late in the first place. “If you are chronically sleep-deprived—which the vast majority of people are—one prolonged sleep doesn’t take care of your sleep debt,” explains Bradley V. Vaughn, professor of Sleep Medicine and Epilepsy at the UNC School of Medicine. “In fact, the average American dedicates less than seven hours to rest when we know that most of us need more. When you have a remaining sleep debt in the morning, this creates a push to want to sleep more.”
Also, since not everybody needs the exact same amount of sleep, it might be hard to tell if your exhaustion is from sleep deprivation or oversleeping, Nowakowski says. One rule of thumb is that if you can fall asleep within half an hour at night, you’re probably not getting too much sleep, unless you have a medical condition that’s causing you to do so. And if you wake up feeling refreshed, you’re probably getting enough sleep and shouldn’t sleep much more.
Another question to ask yourself is whether you’re experiencing sleepiness or fatigue, says Vaughn. Sleepiness—when you feel like you could fall asleep if given the opportunity—is usually a sign that you need more sleep. Fatigue—when you feel exhausted but can’t fall asleep—could also indicate simple sleep deprivation, but could possibly be a sign of an underlying health problem.
In the long-term, you can minimize groggy mornings (or afternoons) by sticking to as consistent a sleep schedule as possible, Vaughn says. Exercise in the morning or afternoon—not near bedtime, which can keep you up—and do something relaxing before bed to cue your body to unwind. And if you’re tired during the day, it’s better to go to bed early than to sleep late the next day.
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