N1: moving from wakefulness into sleep
N1 is the first non-REM stage: the transition between being awake and being asleep. It is not the stage called deep sleep.
Part of non-REM sleep.
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Sleep & Nighttime
Sleep stage mapREM vs deep sleep: interactive sleep stages diagram
Explore the difference between REM and deep sleep with a clickable sleep stage map. Compare N1, N2, N3 and REM, then print the illustrated reference.
Deep sleep is N3, one of the non-REM stages. REM is a separate phase. Explore their places on the map, then compare what the names mean.
A map of names, not a night of data
Two sleep phases. Three non-REM stages.
This map groups categories. Its branches do not show the order, duration or quality of your sleep.
Sleep
Non-REM
Three stages
N1Transition into sleep
N2Asleep, before deeper sleep
N3Deep / slow-wave sleep
REM
A separate phase
REMRapid eye movement sleep
Choose a stage to explore
N3: the stage called deep sleep
N3 is also called slow-wave sleep because of the pattern of brain activity measured in a sleep study. It belongs to non-REM sleep.
People usually spend more time in N3 earlier in the night.
The complete reference
REM vs deep sleep, plus N1 and N2
N2: a non-REM sleep stage
In N2 you are asleep. N2 and N3 are different non-REM stages; the term deep sleep specifically refers to N3.
Part of non-REM sleep.
N3: the stage called deep sleep
N3 is also called slow-wave sleep because of the pattern of brain activity measured in a sleep study. It belongs to non-REM sleep.
People usually spend more time in N3 earlier in the night.
REM: different from deep sleep
During REM, the eyes move rapidly and brain activity is similar to waking activity. Dreaming usually happens during REM, and muscles normally become limp. REM is a separate sleep phase from non-REM N3.
People usually have more REM sleep later in the night.
How are sleep stages identified?
Sleep studies use recorded brain activity and eye movements to classify sleep stages. This diagram explains those categories; it does not measure them.
Wearable estimates depend on the device and its software. This map does not translate a watch’s “light” or “deep” label into a clinical finding or set a target percentage.
Make the most of this tool
See how REM and deep sleep fit into sleep stages
Select N1, N2, N3 or REM to highlight its place on the map and read its explanation. Compare the definitions below, then print the complete stage reference. The map groups stages; it does not show a timed nightly sequence.
Is REM sleep the same as deep sleep?
No. Deep sleep refers to N3, a non-REM stage also called slow-wave sleep. REM is a different sleep phase with rapid eye movements and active brain activity.
Can this diagram tell me whether my sleep tracker numbers are healthy?
No. It explains stage names without assigning a target amount, interpreting a tracker or assessing your sleep. Device estimates vary by model and software; this map is not a recording of your night.
Behind this tool
Research checked October 9, 2026. Original category map and wording based on these sources. Branch size and placement do not represent time or a recommended sleep pattern.