Sleep 101

Stages of Sleep

  • Wake — A spectrum comprising alertness through drowsiness with the eyes open or closed
  • Stage 1 — Very brief stage during which a person is unresponsive, yet easily aroused, comprising about 5% of our sleep
  • Stage 2 — Comprises about half of our night’s sleep during which a person is no longer easily aroused
  • Stage 3 — Deep, restful sleep usually occurring during the first half of the night and directly corresponding to how refreshed we feel the next morning.
  • REM — Deep sleep becoming more frequent during the last half of the night during which most dreaming occurs
  • Arrousal — Occurs when we change to a lighter stage of sleep, for example from Stage 3 to Stage 1. This may happen spontaneously, or be associated with something else, such as an apneic event, or leg movements. The amount of arousals experienced throughout the night may have a direct effect on how refreshed we feel the next morning.