Sleep cycles

When to sleep/wake to rise at a cycle's end

Parameters

Sleep runs in ~90-min cycles: light → deep → REM. Waking at a cycle's end makes rising easier; mid-deep-sleep — grogginess. 5 cycles = 7.5h (optimum for most), 6 = 9h. Sleep debt accumulates — weekend 'catch-up' doesn't fully restore it. Hygiene: consistent wake time, screens −1h, caffeine before 14:00, bedroom 18–20°C.

Go to bed at

21:456 cycles
9h
23:155 cycles
7.5h
00:454 cycles
6h