The Sleep Cycle
This video presents the same text shown beside it, spoken and on screen. It adds nothing the text does not say.
State
The sleep cycle runs N1 to N2 to N3 and back up into REM, repeating roughly every ninety minutes with shifting proportions across the night.
Show
A full night traced hour by hour: the first cycle heavy with N3, the third and fourth carrying long REM periods, and the reason a person woken at six feels different from one woken at two. Every stage transition named as it occurs.