Sleep purpose, circadian rhythm and stages

What this note covers

1. Sleep is an active state with restorative and adaptive functions
2. Circadian and homeostatic processes jointly regulate sleep
3. NREM stages progress from light to slow-wave sleep
4. REM sleep combines active brain signals with muscle atonia
5. Sleep cycles repeat with changing proportions across the night
6. Objective sleep measurement supports bounded functional claims

6 sections · 10 key terms & formulas · 6 common mistakes