A nightly housekeeping system

Sleep isn't passive. During the deepest stages, your brain activates the glymphatic system — a network that flushes out metabolic byproducts that accumulate during waking hours, including proteins linked to cognitive decline.

The four stages, simply

Stage What happens
N1 Drift-off, easy to wake
N2 Light sleep, body temperature drops
N3 Deep sleep, physical restoration
REM Dreaming, memory consolidation

Habits that protect deep sleep

  • Keep a consistent bed and wake time, even on weekends.
  • Get bright light within 30 minutes of waking.
  • Avoid caffeine after early afternoon.
  • Cool, dark, and quiet bedroom — aim for ~18 °C.

Persistent insomnia or loud snoring with daytime fatigue may signal a sleep disorder. A primary-care visit is a sensible first step.