Video: Moving through the stages of sleep

Sleep comes in two different forms: REM (dreaming) and non‑REM (quiet) sleep. In quiet sleep, your brain shifts from chaotic awake activity into calm, rhythmic waves as if a switch has been flipped. In a healthy night, you glide through three deepening stages of non‑REM (N1, N2, N3 slow‑wave sleep) before diving into vivid REM dreams.