You slept eight hours, but your ring or watch is showing a thin little bar for REM, and now you're wondering if that's why you feel foggy. It's one of the most common reasons people go looking for how much REM sleep they actually need.
Here's the short version: most healthy adults need roughly 90 to 120 minutes of REM sleep a night, which works out to about 20 to 25 percent of total sleep. If you're getting the recommended seven to nine hours, that REM usually takes care of itself. Before you panic over a low number on your tracker, though, it's worth knowing how rough those readings can be.
Below is what REM sleep is, how much you need at different ages, what it does for you, and how to get more of it.
How much REM sleep do you need?
Most healthy adults need about 90 to 120 minutes of REM sleep per night, or roughly 20 to 25 percent of their total sleep time. The Sleep Foundation and the National Sleep Foundation both put the adult REM share at about a fifth to a quarter of the night, and on a typical seven-to-nine-hour night that lands in the 90-to-120-minute range.
You don't need to hit that number by hand. REM is one stage in a repeating cycle, and if you sleep enough hours on a regular schedule, your body allocates REM on its own. The target is really “enough good sleep,” not “chase a REM figure.”
Your REM needs also shift with age. According to Baptist Health, a newborn can spend up to half of their sleep in REM, which supports rapid brain development. That share falls through childhood and settles at the adult 20-to-25-percent range by the teen years. In older adulthood, REM tends to dip a bit further, to somewhere around 15 to 20 percent.
Is my sleep tracker's REM number accurate?
Not as accurate as most people assume. Wearables estimate your sleep stages from movement and heart rate, and while they're decent at telling sleep from wake, they're only moderately good at pinpointing REM specifically. So a single low REM reading is a loose estimate, not a verdict.
The research bears this out. A 2024 validation study of popular devices like the Oura Ring, Fitbit, and Apple Watch found their accuracy at distinguishing individual sleep stages ranged from about 50 to 86 percent. A 2025 study in SLEEP Advances found devices over- or underestimated REM by roughly 13 to 15 minutes a night, and a separate 2025 study in the Journal of Sleep Research concluded the trackers it tested were not reliable in clinical practice for measuring REM amount.
None of that means you should toss your tracker. It's genuinely useful for spotting trends over weeks, like whether late drinking or a chaotic schedule is dragging your sleep down. Just don't lose sleep, literally, over one night's REM figure.
What is REM sleep, and what does it do?
REM, or rapid eye movement, sleep is the dreaming stage, when your brain is nearly as active as when you're awake while your body stays temporarily still. Your eyes flick behind closed lids, breathing and heart rate become irregular, and your muscles enter a brief paralysis that keeps you from acting out dreams.
Its real job is up in your head. REM is heavily involved in emotional processing and memory. Research summarized by the NIH describes REM sleep as restoring appropriate next-day emotional reactivity and helping consolidate emotional and autobiographical memories, essentially filing away the day's experiences and taking some of the sting out of the hard ones. That's why a stretch of REM-poor nights can leave you foggy, shorter-tempered, and more reactive.
REM vs deep sleep: what's the difference?
REM and deep sleep are different stages with different jobs, and confusing them is common. The simplest split: deep sleep handles physical restoration, while REM handles the cognitive and emotional side.
Deep sleep, also called slow-wave sleep, is when your body does its heavy repair work, tissue and muscle recovery, immune support, and it dominates the first half of the night. REM does the memory and emotional processing, and it builds up in the later cycles toward morning. You need both, and neither is “better” than the other. Adults typically spend around 10 to 20 percent of the night in deep sleep and 20 to 25 percent in REM.
Where does REM fit in your sleep cycle?
REM comes at the end of each sleep cycle, and those cycles repeat throughout the night. You move through the stages roughly every 90 to 120 minutes, four to five times a night, per the Sleep Foundation and the National Sleep Foundation.
Here's the detail that matters most: REM periods get longer as the night goes on. The first REM stint might be only about 10 minutes, while a later one can stretch toward an hour. Because so much of your REM is back-loaded into the final cycles, cutting your night short, an early alarm, a late bedtime, hitting snooze in the wrong spot, tends to slice off REM before anything else.
How can you get more REM sleep?
The most reliable way to get more REM is to get enough total sleep on a consistent schedule, then remove the things that suppress it. Because REM is concentrated in the later cycles, simply sleeping your full seven to nine hours does most of the work.
A few things that genuinely help:
• Protect your total sleep time. REM is back-loaded, so an extra hour of sleep buys you a disproportionate amount of REM. Guard your wake-up time especially.
• Keep a steady schedule. Going to bed and waking at consistent times keeps your cycles predictable. Irregular timing fragments them.
• Go easy on alcohol at night. Alcohol may help you fall asleep, but it suppresses REM, particularly in the second half of the night.
• Rule out sleep apnea and manage stress. Sleep apnea, high stress, and some medications can all cut into REM. If you snore heavily or feel unrefreshed no matter what, that's worth a doctor's visit.
What happens if you don't get enough REM sleep?
Falling short on REM over time is linked to problems with memory, emotional regulation, and focus. Because REM is when the brain files away memories and processes emotions, skimping on it doesn't just make you tired, it makes you more reactive and forgetful the next day.
That connection is well documented. The NIH-summarized research on sleep and emotion describes how REM sleep restores balanced next-day emotional reactivity; without it, both the brain and behavior struggle to regulate feelings. One rough night won't do lasting harm, and your body will often make up for it with a burst of extra REM the following night. It's the sustained shortfall, night after night, that adds up.
Can you get too much or too little REM sleep?
You can run low on REM, and consistently getting less than about 15 percent of your sleep in REM is often described as low, which can show up as memory, mood, and focus problems. Getting an unusually high amount, on the other hand, is rarely a concern on its own.
A night or two of extra REM is usually just REM rebound, your body catching up after a period of deprivation, illness, or stress. It's a normal correction, not a warning sign. What matters far more than any single night is the overall pattern: enough total sleep, most nights, on a schedule your body can count on.
Frequently asked questions about REM sleep
How many hours of REM sleep do you need?
Most healthy adults need about 1.5 to 2 hours of REM sleep a night, which is roughly 20 to 25 percent of a normal seven-to-nine-hour night. You don't need to target it directly; getting enough total sleep on a regular schedule gets you there on its own.
How much REM sleep should you get by percentage?
Aim for REM to make up about 20 to 25 percent of your total sleep. Newborns run much higher, up to around 50 percent, and the share declines with age, dropping to roughly 15 to 20 percent in older adults. Children and teens sit in the same 20-to-25-percent band as adults.
Is low REM sleep on my tracker something to worry about?
Usually not from one night. Wearables only estimate REM, with accuracy for individual stages ranging from about 50 to 86 percent in validation studies, so a single low reading is unreliable. Look at trends over weeks instead, and see a doctor if you're persistently exhausted.
Does alcohol reduce REM sleep?
Yes. Alcohol can help you fall asleep faster but suppresses REM, especially later in the night as it's metabolized. That's a big reason a few evening drinks can leave you feeling unrested even after a full night in bed.
If you take one thing from all this, let it be this: stop chasing the REM number on your wrist and protect the hours instead. Sleep a consistent seven to nine, ease off the late drinks, and your REM will sort itself out, no math required.