Lesson 8
Sleep Architecture
Read the night as cycles of light, deep and REM sleep, and see what an early alarm or a night awake actually costs.
Builds on
A night is laps, not one long sleep
A night isn't one long sleep. It's four to six laps of a cycle, each around 80 to 100 minutes, and the laps aren't the same. Each passes through stages: N1, the brief doze at the start; N2, steady light sleep; N3, deep or slow-wave sleep; and REM, rapid-eye-movement sleep, when most vivid dreams happen.