I'll be honest here: Sleeping is by far my favorite pastime. I love indulging in a mid-day nap when it's raining outside, and I spend my days fantasizing about when I'll be back in my cozy bed again, eyes closed and dreaming. But sleep is more than just a time to rest and relax. It's actually imperative to our health — so much so that we could even die without it. And REM sleep may be the most important type of all.
"Rapid Eye Movement sleep is that lovely sleep where you have detailed, vivid dreams, like watching a movie," Seema Khosla, MD, the medical director of the North Dakota Center for Sleep, tells Refinery29. "It's actually fairly active. Your eyes move around, we see heart rates go up, and breathing can be irregular." (Never remember your dreams? Don't worry, you're still experiencing REM sleep.)
This sleep cycle is incredibly restorative. If you've ever had the experiencing of waking up on the wrong side of the bed, despite having what felt like a full night's sleep — blame a REM shortfall. "We tend to be cranky and more irritable if we don’t get enough REM sleep," Dr. Khosla says. It may also play a role in memory formation.
Now that you've got the run down on what REM sleep does for us, let's get down to it: Exactly how much of this sleep cycle are we supposed to get each night? The answer to that varies from person to person. "In general, about 20% to 30% of the night [should be] in REM sleep, depending on age," Dr. Khosla explains. That's somewhere around 1.5 to 2.5 hours, if you sleep 8 hours a night. But you don't get it all in a single stretch; the time will be broken up into smaller chunks throughout the night, she says. "REM starts out in short cycles and progressively gets longer towards morning. We usually have our longest stretch of REM right before we wake up."
There are products out on the market that claim to tell you how much REM sleep you're getting, but the best way to measure the quality of your sleep is by how you feel the next day. (In fact, fixating too much on your sleep tracker results can work against you, making it harder to get quality shuteye.) Dr. Khosla poses some questions to ask yourself: Do you feel rested upon awakening? Do you nap during the day? Can you do everything you need to do in the course of a day? Of course, everyone has a sleepy day here and there. But if you regularly feel exhausted at any time other than just before bed, it could mean you're lacking in the REM department.
And if we don't get enough of it... well, it's pretty grim. "We know from animal studies that if we don’t get enough REM, we die," Dr. Khosla says. It sounds dramatic, but it's a thing. She points to an animal study involving a mouse, a flower pot, and water. We'll spare you the depressing details — but basically, they deprived the mouse of its REM cycles. Because of this, the bacteria in the mouse's guts moved into their bloodstreams, and they got septic and died. That's not a fate I'd wish on anyone.
Dr. Khosla points out that, of course, humans are not the same as mice — but she says that the lesson here is still valuable. "It makes us realize that even though we may not understand all there is about sleep, we know that it is important," she says.
So how do we get more REM sleep if we feel like we're missing out? Getting enough of a specific cycle just boils down to getting more sleep in general. For a better night's rest, aim to get some exercise during the day, head to bed early, put down your phone at least two hours before you close your eyes, quit drinking caffeine in the afternoon, and limit alcohol before you hit the hay too.
Some medications may inhibit REM sleep, according to Andrew Weil, MD, founder and director of the Andrew Weil Center for Integrative Medicine at the University of Arizona. So if you're really having a hard time upping the hours you're logging despite your best efforts, chat with your healthcare provider to see if something else is to blame.
All in all, it's worth making it a priority to catch those ZZZ's. After all, it's better to be safe (and well-rested) than end up like those mice. Right?