Sleep stages

Through the night you move through cycles of about 90 minutes. Each cycle passes through lighter and deeper sleep, then REM.

The stages

• Awake: short wakings are normal. Most you won't remember.
• Core (often called light sleep): most of the night. Your body and brain slow down.
• Deep: the slowest, most restorative stage. Most of it comes early in the night.
• REM: when most dreaming happens. Longer REM spells come towards morning.

Where Soma gets them

From your watch, ring or sleep pad, through Apple Health. Wearables estimate stages from movement, heart rate and breathing, so they're a good guide rather than a lab result.

In Soma's sleep score

Sleep weighs how long you slept against what you need first, then how efficient and unbroken your night was, your deep and REM sleep, and how far your heart rate dropped. Deep and REM are measured against targets for your age.

REM and deep sleep each have their own history in the Vault, in the Soma section. See Scores and what moves them.

Getting more deep and REM

A regular bedtime, a dark and cool room, no alcohol or late meals, and enough time in bed help most. Track's tags and Trends show what moves yours.

If a night has hours but no stages, or Soma asks for time in bed, see Sleep has no stages or time in bed.