Sleep Calculator

This tool recommends wake-up or bedtimes based on the idea that healthy sleep is composed of ~90-minute cycles and that it takes about 14 minutes to fall asleep. Given a bedtime it suggests four wake-up times for 6, 5, 4, and 3 cycles; given a wake-up time it suggests the matching bedtimes. 6 cycles is labelled Best, 5 Good, and 4/3 Minimum.

1. Choose mode: 'I want to sleep now' (enter bedtime, get wake times) or 'I need to wake at' (enter wake time, get bedtimes). 2. Set the time using the time picker. 3. Optionally click 'Use current time' to fill it. 4. Read the four suggested times. 5. Click any suggested row to copy that time into the opposite field (e.g. clicking a wake time in sleep mode fills the wakeTime input).

CYCLE_MINUTES = 90 and FALL_ASLEEP_MINUTES = 14; candidate cycle counts are [6, 5, 4, 3]. Sleep mode (predict wake): wakeTime = sleepTime + (cycles × 90 + 14) minutes. Wake mode (predict bed): bedTime = wakeTime − (cycles × 90 + 14) minutes. So for 6 cycles the tool schedules 9 hours 14 minutes of total time in bed (540 min of sleep + 14 min to fall asleep). Times are displayed in 24-hour HH:MM.