REM sleep should make up about 20% to 25% of your total sleep time. For someone sleeping eight hours, that works out to roughly 90 to 120 minutes of REM per night. This target applies to healthy adults, though the percentage shifts significantly at different life stages.
Why REM Sleep Matters
REM sleep is the stage when your brain is most active, close to waking levels. During this phase, your brain prunes the connections between brain cells, which strengthens memory and sharpens problem-solving abilities. It’s also when your brain processes emotional memories, including fear-related ones, helping regulate your mood the following day.
For infants and young children, REM sleep plays an even more critical role: it supports the development of the central nervous system, including the brain and spinal cord. This is why newborns spend a far greater proportion of their sleep in REM than adults do.
How REM Changes With Age
Newborns get the most REM sleep of any age group and can enter REM almost immediately after falling asleep. As children grow, the proportion of REM gradually decreases and stabilizes in the 20% to 25% range during adulthood. Older adults typically need less REM sleep than younger adults, children, and babies, and their REM periods tend to be shorter.
How REM Fits Into a Night of Sleep
You cycle through multiple sleep stages roughly every 90 minutes throughout the night, moving from light sleep to deep sleep to REM. Your first REM period is short, often just a few minutes. Each successive cycle brings a longer REM period, so the bulk of your REM sleep happens in the second half of the night. This is one reason cutting your sleep short by even an hour or two disproportionately reduces your REM time.
What Happens When REM Drops Too Low
Getting less REM sleep than your body needs carries real health consequences. A study funded by the National Heart, Lung, and Blood Institute found that for every 5% reduction in REM sleep, death rates increased 13% to 17% among the older men studied. Researchers observed similar results in a separate group of middle-aged men and women. In both groups, insufficient REM sleep was associated with early death from any cause.
Beyond mortality risk, poor REM sleep is linked to heart disease and high blood pressure. On a day-to-day level, you’re likely to notice the effects as difficulty concentrating, trouble retaining new information, and increased emotional reactivity.
Why Your REM Percentage Might Be Unusually High
Sometimes a sleep tracker shows REM percentages well above 25%. This is often a phenomenon called REM rebound, where your brain temporarily compensates for a period of suppressed REM by spending extra time in that stage.
Several common triggers cause REM rebound:
- Sleep deprivation. Missing 12 or more hours of sleep increases both REM and non-REM recovery sleep. Extreme sleep deprivation (96+ hours) produces especially pronounced REM rebound.
- Alcohol and cannabis. Both suppress REM sleep while you’re using them. When you stop, your brain overcompensates with longer, more intense REM periods.
- Antidepressants and sleep medications. Many antidepressants, benzodiazepines, and barbiturates suppress REM. Discontinuing them can trigger a temporary spike in REM sleep.
- Stress. Animal studies show REM rebound can begin after just 30 minutes of exposure to a stressor, with the percentage of REM increasing as stress duration climbs.
- Starting CPAP therapy. People with obstructive sleep apnea often experience REM rebound when they first begin using a CPAP machine, because the device allows them to reach REM stages their apnea had been disrupting.
REM rebound is generally temporary and is your brain’s way of catching up on a sleep stage it was missing.
How to Protect Your REM Sleep
Since REM concentrates in the later sleep cycles, the single most effective thing you can do is sleep long enough. If you consistently cut nights to six hours, you’re losing a disproportionate share of REM. Aiming for seven to nine hours gives your brain enough cycles to accumulate the full 20% to 25%.
Alcohol is one of the most common REM disruptors. Even moderate drinking in the evening suppresses REM in the first half of the night. Limiting alcohol, especially within three to four hours of bedtime, helps preserve normal sleep architecture. The same applies to cannabis, which suppresses REM during regular use.
Consistency matters too. Going to bed and waking up at roughly the same time trains your body’s internal clock to move through sleep stages efficiently. Irregular schedules fragment sleep cycles and reduce time spent in both deep sleep and REM.