REM sleep makes up about 25% of your total sleep time, and most of it happens in the second half of the night. That means the single most effective way to get more REM sleep is to sleep longer, since cutting your night short by even an hour disproportionately cuts into REM. Beyond total sleep time, several specific habits, environmental factors, and substances either protect or disrupt your REM cycles.
Why REM Concentrates Late in the Night
Your brain cycles through sleep stages roughly every 90 minutes. In the first couple of cycles, deep sleep dominates and REM periods are short, sometimes just a few minutes. As the night progresses, deep sleep shrinks and REM periods grow longer. By your fourth or fifth cycle, a single REM period can last 30 to 60 minutes.
This back-loaded pattern explains why people who sleep six hours instead of eight often show the biggest losses in REM. You’re not just trimming a little off each stage. You’re cutting out the longest, most dream-rich portion of the night entirely. If you suspect your REM sleep is low, the first question to ask is whether you’re consistently getting seven to nine hours of total sleep.
Keep Your Bedroom Cool
Room temperature has a direct effect on how stable your REM sleep is. Heat is one of the biggest environmental disruptors of REM. When your body can’t cool down sufficiently, it struggles to maintain the longer REM periods that occur in the early morning hours.
The optimal bedroom temperature for adults is 60 to 67°F (15 to 19°C). This range helps facilitate stable REM sleep throughout the night. Above 70°F, sleep quality drops noticeably. Below 60°F, the cold itself becomes disruptive. If you tend to sleep warm, lighter bedding, a fan, or cooling your room before bed can make a measurable difference.
How Alcohol Suppresses REM Sleep
Alcohol is one of the most common and most underestimated REM disruptors. Even moderate drinking in the evening suppresses REM sleep during the first half of the night. Your brain then tries to compensate with a “REM rebound” in the second half, producing unusually intense, fragmented dream periods that don’t deliver the same restorative benefit as normal REM.
The effect isn’t limited to heavy drinking. A couple of glasses of wine with dinner can measurably reduce your REM percentage for that night. For people with long-term heavy alcohol use, the damage to REM regulation can persist even during extended sobriety, suggesting that chronic alcohol exposure may cause lasting changes to the brain mechanisms that control REM cycles. If you’re trying to increase your REM sleep, reducing or eliminating alcohol, especially within three to four hours of bedtime, is one of the highest-impact changes you can make.
Medications That Affect REM
Several widely prescribed medications alter REM sleep. Antidepressants, particularly SSRIs and SNRIs, are well-known REM suppressors. They don’t just reduce the amount of REM sleep; they also interfere with the normal muscle paralysis that occurs during dreaming. This paralysis is your brain’s way of preventing you from physically acting out dreams, and when it’s disrupted, sleep becomes less restful.
If you’re taking an antidepressant and notice changes in your dreaming or sleep quality, that’s worth discussing with your prescriber. Switching medications or adjusting timing can sometimes help, but stopping an antidepressant to chase better REM sleep is rarely the right trade-off. The goal is to find the best balance for your overall health.
Exercise: Helpful Overall, Complicated for REM
Regular physical activity consistently improves total sleep quality, helps you fall asleep faster, and increases deep sleep. Its relationship with REM sleep specifically is more nuanced. Acute bouts of intense exercise can temporarily reduce REM sleep on the night following the workout, likely because the body prioritizes deep sleep for physical recovery.
Over time, though, consistent aerobic exercise tends to normalize sleep architecture across all stages. The key is regularity rather than intensity. A sustained habit of moderate activity, like brisk walking, cycling, or swimming most days, supports healthier sleep cycles overall. Timing matters too: vigorous exercise within two to three hours of bedtime can raise your core body temperature enough to delay sleep onset and compress your early sleep cycles, indirectly reducing total REM time.
Maintain a Consistent Sleep Schedule
Your brain’s internal clock governs when REM sleep is most likely to occur. REM is tightly linked to your circadian rhythm, peaking in the early morning hours roughly aligned with your body’s temperature minimum. When you go to bed and wake up at wildly different times, your circadian clock and your sleep cycles fall out of sync. The result is that your brain may not be primed for its longest REM periods when you actually need them.
Keeping a consistent bedtime and wake time, even on weekends, helps your body reliably hit those late-night REM windows. A shift of more than an hour in either direction on weekends (sometimes called “social jet lag”) is enough to disrupt this alignment for several days.
Caffeine and Its Timing
Caffeine blocks the brain’s sleep-pressure signals, and its effects last far longer than most people realize. Its half-life is five to six hours, meaning half the caffeine from a 2 p.m. coffee is still circulating at 7 or 8 p.m. Even if you fall asleep on schedule, residual caffeine can reduce deep sleep and fragment the sleep cycles that lead into REM. Cutting off caffeine by early afternoon, or by noon if you’re sensitive, protects your later sleep architecture.
Magnesium Supplements
Among supplements marketed for sleep, magnesium has some of the more promising evidence specifically for REM. In a randomized controlled trial, adults with sleep problems who took 1 gram per day of magnesium L-threonate for 21 days showed significant improvements in both deep sleep and REM sleep scores compared to placebo. They also reported better mood, energy, and daytime alertness.
Not all forms of magnesium are equivalent. Magnesium L-threonate crosses the blood-brain barrier more effectively than common forms like magnesium oxide or citrate, which may explain why it showed effects on sleep architecture specifically. Magnesium glycinate is another form often recommended for sleep, though it has less direct evidence for REM improvement. Melatonin, by contrast, primarily helps with sleep onset and circadian timing rather than increasing time spent in REM.
What’s Happening in Your Brain During REM
Understanding the biology can help explain why certain strategies work. REM sleep is driven largely by acetylcholine, a neurotransmitter that surges during dreaming. Acetylcholine activates specific receptors in the brainstem that trigger the hallmarks of REM: rapid eye movements, vivid dreams, and full-body muscle paralysis. Anything that supports healthy acetylcholine signaling, like adequate sleep duration and avoiding substances that interfere with it, supports REM.
This is also why alcohol and certain medications are so effective at suppressing REM. They interfere directly or indirectly with this acetylcholine-driven system. Your brain doesn’t just passively drift into REM; it actively switches into a distinct neurological state, and that switch depends on the right chemical conditions being in place.
Tracking Your Progress
Consumer wearables like the Oura Ring, Apple Watch, and Fitbit estimate REM sleep using heart rate variability and movement patterns. These aren’t as precise as a clinical sleep study, but they’re useful for spotting trends over weeks. If you make a change, like dropping alcohol or cooling your bedroom, look for patterns across 10 to 14 nights rather than comparing individual nights. Night-to-night variation is normal, and a single bad night doesn’t mean the strategy isn’t working.
For a healthy adult, roughly 90 minutes of REM per night (about 25% of an eight-hour sleep) is a reasonable target. If your tracker consistently shows REM below 15% of your total sleep, and you’re sleeping long enough, that’s a signal worth investigating with the changes outlined above.