Sleep Stages and Dreaming: What Happens in REM

Sleep is divided into stages that repeat through the night: non-REM sleep, which has three stages from light to deep, and REM sleep, named for the rapid eye movements that mark it. Dreaming occurs in both, but vivid, story-like dreams are most common in REM.

What are the stages of sleep?

Sleep scoring standards divide sleep into wake, three non-REM stages (N1 to N3) and REM (Source 3). N1 is the light drift into sleep, N2 is a steadier light sleep and N3 is the deep, slow-wave stage. REM sleep follows, and then the cycle starts again.

A full cycle lasts roughly 90 minutes in adults, and a night holds several of them. Deep sleep is concentrated in the first half of the night, while REM periods grow longer in the second half.

What is REM sleep?

REM sleep was identified in 1953, when researchers reported regular periods of rapid eye movement during sleep and found that people woken from them often described dreams (Source 1). In REM, brain activity looks different from deep sleep and more like waking, while the large voluntary muscles are largely switched off. That muscle state is why you do not usually act out what you dream.

The finding changed the field. Dreaming became something that could be studied in a laboratory, with a recordable stage attached to it.

Do we only dream in REM?

No. Reviews of dream research report dream experiences from non-REM sleep too, though the character differs: REM reports tend to be longer, more vivid and more narrative, while non-REM reports tend to be shorter and more thought-like (Source 2). The picture is more varied than "REM equals dreaming".

For a reader keeping a journal, the practical point is simple: any dream you remember counts, whichever stage it came from.

When do you dream most?

Because REM periods lengthen as the night goes on, the dreams most likely to be in your memory at waking come from the final hours. That is one reason a morning alarm that cuts a night short can mean fewer remembered dreams. You can read more about recall in why we forget dreams.

The same timing is why intense dreams such as the ones covered in what causes nightmares are reported more often toward morning.

What does this mean for your dream journal?

You do not need to know your sleep stages to keep a record. What helps is a calm waking: lie still for a moment, run the dream through once and write it before the day pushes it away. Images such as a staircase or a house are easiest to catch in those first minutes.

If you want to go further into one unusual form of REM dreaming, see what lucid dreaming is.

How do sleep stages shape the way you wake?

Waking from different stages feels different. If your alarm pulls you out of deep sleep, you are often groggy and remember little. If you wake in or near REM sleep, dream images are still close, and recall is easier. This is a general pattern reported in sleep research, and the exact timing differs between people and nights.

A practical consequence is that you cannot choose which stage you wake from, but you can change how you wake. A gentle alarm, a consistent wake time and a few quiet moments before moving all help you catch what remains of the dream. A phone alarm that blares and demands a response works against you.

Does dreaming get shorter or longer through the night?

Longer. Early in the night, REM periods are brief, often only a few minutes. By the final cycles they can last much longer, and the dreams within them tend to be more elaborate. If you sleep six hours instead of eight, you lose a disproportionate share of REM sleep, because the longest REM periods sit at the end.

That is a fact about how sleep is organised, not advice about how long you should sleep; individual needs differ, and a doctor is the right person to ask about your own sleep.

For someone keeping a journal, the lesson is modest and useful: the dreams you remember on a normal morning are a sample, weighted toward the last stretch of the night. Reading your entries with that in mind keeps expectations realistic. A short entry or a blank one is ordinary, since no night delivers the same amount of dream material twice, and a longer, more vivid one is not necessarily more important.

Where does Onira fit in?

Onira does not measure sleep stages. It is a place for the dream itself: you type or speak it, and Onira keeps it with a reflection and a scene sequence. You can look at the features or download Onira to try it.