REM sleep explained
Last reviewed: 14 September 2026
REM is the strangest part of the night: a brain running at close to waking activity inside a body that has been temporarily switched off. It is also the part a short night takes first.
About 20–25% of your night
REM sleep makes up roughly a quarter of a healthy night — about 90 minutes to 2 hours for most adults. It is the stage where most vivid dreaming happens, and where a great deal of emotional processing and memory consolidation takes place.
The defining feature of REM is the contradiction inside it: brain activity close to waking levels, while the body is temporarily paralysed so you do not act out what you are dreaming.
What REM sleep is
REM stands for rapid eye movement — the eyes dart about under closed lids, which is how the stage was first identified in the 1950s. Everything else about it is unusual too. Breathing and heart rate become irregular, body temperature regulation is suspended, and the major muscle groups are actively paralysed.
That paralysis is a safety mechanism. When it fails, people physically act out their dreams — a recognised condition called REM sleep behaviour disorder, which is worth seeing a GP or doctor about. When it lingers a moment after you wake, you get sleep paralysis, which is frightening but harmless.
REM builds up towards morning
REM is distributed almost exactly opposite to deep sleep. The first REM period of the night lasts around ten minutes; each one afterwards is longer, and the last can run close to an hour.
Because REM is concentrated in the last cycles, cutting an hour off the end of your night removes a disproportionate amount of it. Someone sleeping five hours instead of eight has lost most of their REM and very little of their deep sleep — which is why short nights tend to show up as a short fuse and a leaky memory rather than as physical exhaustion.
It is also why you usually remember dreams from just before waking: those are the long REM periods, and you were closest to the surface.
How much REM sleep do you need?
| Total sleep | Roughly how much REM |
|---|---|
| 9 hours | About 2 hours |
| 7½ hours | About 1 hour 40 minutes |
| 6 hours | About 1 hour 15 minutes |
| 4½ hours | About 40 minutes — a large shortfall |
Newborns are the striking exception: REM makes up around half of their sleep, far more than at any later point, which is thought to relate to how much neural development is happening.
What suppresses REM
- Alcohol. The most common culprit. It shortens the time to fall asleep and then markedly suppresses REM in the first half of the night, with fragmented sleep afterwards.
- Short nights. By far the largest effect, for the reason above.
- Cannabis. Regular use suppresses REM; stopping produces a rebound with unusually vivid and often unpleasant dreams.
- Some antidepressants, particularly SSRIs, substantially reduce REM. This is a known effect and not a reason to stop a prescribed medicine — discuss it with your GP rather than acting on it.
Stop any of the first three and you will often get a REM rebound: the body repays what it is owed, with a few nights of intense dreaming. It is a sign of recovery rather than a problem.
How to get more REM sleep
There is no trick, and that is the honest answer. Because REM sits at the end of the night, the way to get more is to be asleep for the part of the night where it happens:
- Sleep the full 7 to 9 hours rather than cutting the last cycle.
- Keep your wake-up time consistent, so the last cycles actually complete.
- Leave a gap between the last drink and bed — or skip it.
- Treat anything fragmenting your sleep. Untreated sleep apnoea in particular disrupts the second half of the night, which is where REM lives.
Sources. Sleep stage proportions and durations are from published polysomnography data and the American Academy of Sleep Medicine; duration recommendations are from the AASM and the National Sleep Foundation. This page is general wellbeing information, not medical advice — speak to a GP or doctor about persistent sleep problems.
Common questions
What is REM sleep?
Rapid eye movement sleep — the stage with brain activity close to waking levels, irregular breathing and heart rate, and the major muscles temporarily paralysed. Most vivid dreaming happens in REM, along with emotional processing and much memory consolidation.
How much REM sleep do you need?
About 20 to 25% of your total sleep, which is roughly 90 minutes to 2 hours for most adults on a normal night.
How long is a REM cycle?
REM is a stage within a sleep cycle rather than a cycle of its own. The first REM period of the night lasts around ten minutes; they get longer through the night, and the final one can run close to an hour.
Why do I remember dreams just before waking?
Because the longest REM periods come at the end of the night, and you are closest to the surface then. Dreams from earlier, shorter REM periods are far less likely to be recalled.
Does alcohol affect REM sleep?
Yes, considerably. Alcohol gets you to sleep faster and then suppresses REM in the first half of the night and fragments the second half. Stopping after regular use often produces a REM rebound with unusually vivid dreams.
How can I get more REM sleep?
Sleep longer, and keep your wake-up time consistent so the last cycles complete — REM is concentrated at the end of the night, so cutting an hour off the end removes a disproportionate amount of it. Reducing evening alcohol helps too.