Sleep Cycle API

Sleep-cycle planning as an API, built around the fact that a full sleep cycle averages about 90 minutes and that waking at the end of a cycle — rather than mid-cycle — leaves you feeling more refreshed. The bedtime endpoint takes a wake-up time and suggests the times to fall asleep so that you wake at the end of a whole number of cycles (6, 5, 4 or 3 cycles), allowing for the time it takes to drift off. The wake-time endpoint does the reverse: from a bedtime (or "now") it suggests the best times to set an alarm. The duration endpoint takes a bedtime and a wake time and reports time in bed, actual sleep, the number of full cycles, how many minutes you are into the current cycle and how close you are to a clean cycle boundary, with a healthy-duration assessment. The nap endpoint plans power, short, slow-wave and full-cycle naps from a start time and explains the trade-offs. All clock maths is modulo 24 hours and accepts both 24-hour ("23:15") and 12-hour ("10:30 PM") times. Everything is computed locally and deterministically, so it is instant and private. Ideal for sleep, alarm-clock and wellbeing apps, smart-home routines, shift-work planning and productivity tools. Pure local computation — no key, no third-party service, instant. Live, nothing stored. INFORMATIONAL ONLY — sleep needs vary by individual; not medical advice. 4 endpoints. This is sleep-cycle timing maths; for time-zone conversion use a time API and for body metrics such as BMI use a health-calculator API.