Dream science
Do you only dream in REM sleep?
You don’t only dream in REM (rapid eye movement) sleep (NINDS, 2025). Studies have found dream reports after up to 70% of awakenings from non-REM sleep, the other main kind of sleep (Siclari et al., 2017). REM dreams do tend to be longer, more vivid and more emotional, and REM periods get longer toward morning, so the night’s most vivid dreams often come late (Nir & Tononi, 2010; NINDS, 2025).
Last updated: 2026-10-13.
Why did scientists link dreaming to REM sleep?
Scientists linked dreaming to REM sleep because of what the first sleep-lab studies found. Dement and Kleitman (1957) reported that people recalled dreams far more often when woken during periods of rapid eye movements than when woken at other times. Nir and Tononi (2010) put the early figures at 74–80% of REM awakenings against 7–9% of non-REM ones. With a gap that wide, they write, it seemed natural to call REM the dreaming stage, and for a time, reports from non-REM sleep were written off as memories of earlier REM dreams or as something made up while confused on waking.
When researchers stopped asking about dreams and asked people to describe anything going through their mind just before they woke, reports from non-REM sleep rose to between 23% and 74% of awakenings (Nir & Tononi, 2010).
The reverse happens too: in a small but steady share of REM awakenings, people report no experience at all (Siclari et al., 2017). REM sleep makes a dream report more likely, but it isn’t required for one (Nir & Tononi, 2010).
How are non-REM dreams different from REM dreams?
Non-REM dreams are, on average, shorter and closer to thinking than REM dreams (Nir & Tononi, 2010). Compared with REM reports, they tend to be less vivid and less visual, more plausible, more about current concerns and less emotional. A later review agrees that vivid, emotional dreams are more common after REM awakenings (Scarpelli et al., 2019).
The difference isn’t fixed, though. Late in the night, non-REM reports grow much longer and more dreamlike, and 10–30% of all non-REM reports can’t be told apart from REM reports by any measure (Nir & Tononi, 2010). Since non-REM sleep fills about 75% of total sleep time, these dreams make up a significant share of all full-fledged dreams.
What do people report when woken from each stage?
What people report depends on the stage and on the time of night (Nir & Tononi, 2010). Sleep studies split non-REM sleep into three stages, N1 to N3, from the lightest to deep sleep (National Heart, Lung, and Blood Institute [NHLBI], 2022).
| Stage | When it happens | How often people report something | What it tends to be like |
|---|---|---|---|
| N1, the lightest stage | As you fall asleep; usually lasts several minutes (National Institute of Neurological Disorders and Stroke [NINDS], 2025) | 80–90% of awakenings (Nir & Tononi, 2010) | Very short; vivid images, often still like snapshots (Nir & Tononi, 2010) |
| N2, light sleep | Through the night, before deeper sleep; more of your sleep than any other stage (NINDS, 2025) | 50–70% for N2 and N3 together (Nir & Tononi, 2010) | Shorter and more thought-like than REM reports, less so late in the night (Nir & Tononi, 2010) |
| N3, deep sleep | Mostly in the first half of the night (NINDS, 2025; NHLBI, 2022) | Few reports early in the night, when deep sleep dominates (Nir & Tononi, 2010) | Hard to judge, because people woken from deep sleep are often disoriented (Nir & Tononi, 2010) |
| REM | First about 90 minutes after you fall asleep, then in longer periods later in the night (NINDS, 2025) | 80–90% of awakenings in adults (Nir & Tononi, 2010) | Vivid, story-like and often emotional (Nir & Tononi, 2010; NINDS, 2025) |
How does a night of sleep cycles unfold?
A night of sleep runs in loops. You move through non-REM and REM sleep in a cycle that starts over every 80 to 100 minutes, usually four to six times a night (NHLBI, 2022). You may wake briefly between cycles, and deep sleep comes mostly early in the night, REM sleep mostly later.
The first REM period arrives about 90 minutes after you fall asleep (NINDS, 2025). It’s typically the shortest, at around 10 minutes, and each one after it is longer, up to an hour (Cleveland Clinic, 2023). The longer a REM period lasts, the longer its dream reports (Nir & Tononi, 2010), as the guide to how long REM dreams run explains.
Why are your morning dreams the vivid ones?
Several things that make dreams vivid build up toward morning. REM periods grow longer later in the night (NINDS, 2025).
Your body clock adds to it. In one study, people were woken from REM and non-REM sleep twice: near the low point of their body temperature in the night, and again in the late morning (Wamsley et al., 2007). Their dream reports rose and fell with both the sleep cycle and the daily rise in brain activation, and REM sleep added emotional intensity. Antrobus et al. (1995) came to a similar view: vivid dream images depend on a kind of brain activation found both in REM sleep and in the body clock’s morning rise.
A morning dream is also often the one you wake up from. That helps explain why the last dream of the night sticks, because unless the dreamer wakes up, most dreams are lost (Nir & Tononi, 2010). If your dreams have been intense for weeks, see dreams that feel unusually vivid lately.
Why can you dream the moment you fall asleep?
You can dream as you fall asleep because the first stage of sleep makes images of its own (Nir & Tononi, 2010). People woken from N1 report something 80–90% of the time, though the reports are very short. These are mostly vivid images, often still like single snapshots, and the dreamer is usually not in them. Researchers call them hypnagogic hallucinations. What you did before bed can show up: after long sessions of the computer game Tetris, people often saw falling blocks as they drifted off.
Full dreams can also come before any REM sleep at all (Nir & Tononi, 2010). People sometimes report them after waking from the first non-REM stretch of the night, and even from naps made up only of non-REM sleep. That’s how a short nap can hold a dream, even though the first REM period usually starts about 90 minutes into sleep (NINDS, 2025).
What decides whether you are dreaming at all?
Whether you’re dreaming may depend more on one part of the brain than on the sleep stage. Siclari et al. (2017) recorded brain waves in fine detail while waking people again and again through the night. They studied 32 people over 233 awakenings, and 7 trained people over 815. In both REM and non-REM sleep, reports of dreaming went with less slow brain-wave activity in a region at the back of the brain that the authors call a posterior “hot zone.”
In a third experiment, with 7 more people, watching that zone in real time predicted whether someone woken from non-REM sleep would report a dream. It was right 87% of the time overall (Siclari et al., 2017). As the authors note, the sleep stage alone can’t tell you whether someone is experiencing anything.
More questions about REM sleep and dreams
Is REM sleep the same as deep sleep?
REM sleep and deep sleep are different stages (NHLBI, 2022). Deep sleep is stage 3 of non-REM sleep, also called slow-wave sleep, and you usually spend more time in it early in the night. In REM sleep, brain activity looks similar to waking, and you usually have more of it later in the night.
Do children dream in REM sleep the way adults do?
Young children report dreams from REM sleep far less often than adults (Nir & Tononi, 2010). In a series of studies by David Foulkes, children under 7 reported dreaming only 20% of the time when woken from REM sleep, compared with 80–90% in adults. Preschoolers’ dreams were often static and plain, such as seeing an animal.
Why do I remember morning dreams better?
Morning dreams have two advantages. The night’s last REM periods are its longest (NINDS, 2025), and you often wake straight out of a dream. That matters, because dreams you don’t wake from are mostly lost (Nir & Tononi, 2010).
Catch the morning dream
With Dreams Come True, a voice-first dream journal app for iPhone, you can tell a morning dream out loud before it fades. The speech is transcribed on the phone, and the audio never leaves it.
Sources
- Antrobus, J., Kondo, T., Reinsel, R., & Fein, G. (1995). Dreaming in the late morning: Summation of REM and diurnal cortical activation. Consciousness and Cognition, 4(3), 275–299. doi.org/10.1006/ccog.1995.1039
- Cleveland Clinic. (2023, June 19). Sleep: What it is, why it’s important, stages, REM & NREM. my.clevelandclinic.org/health/body/12148-sleep-basics
- Dement, W., & Kleitman, N. (1957). The relation of eye movements during sleep to dream activity: An objective method for the study of dreaming. Journal of Experimental Psychology, 53(5), 339–346. doi.org/10.1037/h0048189
- National Heart, Lung, and Blood Institute. (2022, March 24). How sleep works: Sleep phases and stages. National Institutes of Health. nhlbi.nih.gov/health/sleep/stages-of-sleep
- National Institute of Neurological Disorders and Stroke. (2025, February 25). Brain basics: Understanding sleep. National Institutes of Health. ninds.nih.gov/health-information/public-education/brain-basics/brain-basics-understanding-sleep
- Nir, Y., & Tononi, G. (2010). Dreaming and the brain: From phenomenology to neurophysiology. Trends in Cognitive Sciences, 14(2), 88–100. doi.org/10.1016/j.tics.2009.12.001
- Scarpelli, S., Bartolacci, C., D’Atri, A., Gorgoni, M., & De Gennaro, L. (2019). The functional role of dreaming in emotional processes. Frontiers in Psychology, 10, Article 459. doi.org/10.3389/fpsyg.2019.00459
- Siclari, F., Baird, B., Perogamvros, L., Bernardi, G., LaRocque, J. J., Riedner, B., Boly, M., Postle, B. R., & Tononi, G. (2017). The neural correlates of dreaming. Nature Neuroscience, 20(6), 872–878. doi.org/10.1038/nn.4545
- Wamsley, E. J., Hirota, Y., Tucker, M. A., Smith, M. R., & Antrobus, J. S. (2007). Circadian and ultradian influences on dreaming: A dual rhythm model. Brain Research Bulletin, 71(4), 347–354. doi.org/10.1016/j.brainresbull.2006.09.021