Most adults need about two hours of REM sleep each night. That works out to roughly 25% of your total sleep time, so hitting seven to eight hours of sleep generally gets you there naturally. There’s no official medical guideline setting a strict REM minimum, but the research on what happens when you fall short makes a strong case for protecting those two hours.
How REM Fits Into a Full Night of Sleep
Your brain cycles through multiple sleep stages each night, typically completing four to six full cycles. Each cycle lasts roughly 90 minutes and moves through progressively deeper stages of non-REM sleep before arriving at a REM period. The key detail: your first REM period of the night is short, often just a few minutes, while the later ones grow longer. Most of your REM sleep is packed into the final third of the night.
This back-loaded pattern explains why cutting your sleep short by even an hour or two can disproportionately slash your REM time. If you normally sleep eight hours but set your alarm for six, you’re not just losing 25% of your sleep. You’re losing a much larger share of your REM sleep, because you’re chopping off the part of the night where the longest REM periods occur.
What REM Sleep Does for Your Brain
REM sleep is the stage most closely associated with vivid dreaming, but the brain is doing more than generating storylines. During REM, your brain displays electrical activity that closely resembles wakefulness, and researchers have long considered it central to reprocessing the experiences you had during the day. It plays a role in consolidating memories, particularly ones with an emotional component, and in integrating new information with what you already know.
The precise mechanisms are still being refined. Early studies on REM deprivation showed clear memory and mood effects, though some of those findings were complicated by the stress of being repeatedly woken up (which is how researchers selectively deprive people of REM in a lab). What’s less debatable is the population-level data on long-term REM loss.
The Health Risks of Too Little REM
A large study highlighted by the National Heart, Lung, and Blood Institute found that insufficient REM sleep was associated with a higher risk of death among middle-aged and older adults. The numbers were striking: for every 5% reduction in REM sleep as a share of total sleep, death rates increased by 13% to 17%. The researchers observed this pattern in two separate groups, older men and a mixed group of middle-aged men and women, and the association held in both.
This doesn’t mean a single bad night of REM sleep is dangerous. The concern is chronic, ongoing deficits. Poor sleep quality in general has been linked to heart disease and high blood pressure, and REM loss appears to carry its own independent risk on top of those broader effects.
REM Needs Across Age Groups
Two hours is the adult benchmark, but REM needs shift dramatically over a lifetime. Newborns spend around eight hours a day in REM sleep, roughly half their total sleep time. This is thought to support the rapid brain development happening in the first year of life. As children grow, the proportion of REM sleep gradually decreases, settling into the adult pattern of about 25% by the teenage years.
In older adults, REM sleep tends to decline further, both in total duration and as a percentage of the night. This natural reduction may partly explain why the mortality research found older adults to be particularly vulnerable to additional REM losses from disrupted sleep, medications, or lifestyle factors.
What Reduces Your REM Sleep
Alcohol is one of the most common REM disruptors. Drinking before bed may help you fall asleep faster, but it fragments your sleep throughout the night. Each time you partially wake up, your brain resets to a lighter sleep stage instead of cycling into REM. The result is less total REM sleep even if you spend a full eight hours in bed. The Cleveland Clinic notes that adding alcohol to the mix leads to “more fragmentation and less likelihood of REM sleep.”
Other factors that can cut into REM time include irregular sleep schedules, sleep disorders like obstructive sleep apnea (which causes repeated awakenings), and certain medications, particularly some antidepressants, which are well known to suppress REM. If you’re on a medication and noticing unrefreshing sleep or a lack of dreaming, it’s worth raising the question with your prescriber.
Caffeine consumed too late in the day, high stress, and sleeping in a noisy or bright environment can all reduce sleep quality broadly, which tends to pull down REM time along with it.
How to Get More REM Sleep
Because REM sleep is concentrated in the last few hours of the night, the single most effective strategy is simply sleeping long enough. If you’re consistently getting less than seven hours, your REM time is almost certainly below two hours. Extending your sleep by even 30 to 60 minutes can add a meaningful chunk of REM.
Beyond total sleep time, consistency matters. Going to bed and waking up at roughly the same time each day helps your brain settle into a predictable cycle pattern, which makes it easier to reach and sustain those later, longer REM periods. Avoiding alcohol for at least three to four hours before bed removes one of the biggest lifestyle-related REM suppressors.
Can You Track Your REM Sleep at Home?
Consumer wearables like smartwatches and fitness rings estimate your sleep stages using heart rate, movement, and sometimes blood oxygen data. These devices can give you a general sense of your sleep patterns and trends over time, but they are not as accurate as a clinical sleep study, which uses brain wave monitoring to identify sleep stages precisely. If your tracker shows a consistent pattern of very low REM percentages night after night, that’s worth paying attention to as a signal, but don’t stress over the exact numbers on any single night.
REM sleep naturally varies from night to night. One night at 15% and the next at 30% is normal. What matters is the overall pattern across weeks, not any individual reading.