Sleep Cycle & Bedtime Calculator

Optimize your sleep quality and eliminate morning grogginess (sleep inertia) with the Sleep Cycle & Bedtime Calculator. Human nocturnal rest is structured into predictable 90-minute ultradian sleep cycles progressing from light sleep (NREM Stage 1 & 2), through restorative slow-wave deep sleep (NREM Stage 3), into Rapid Eye Movement (REM) sleep where dreams and neural plasticity occur. Waking up mid-cycle during deep slow-wave sleep leaves you fatigued and cognitively impaired, while waking up at the completion of a 90-minute cycle ensures natural alertness, high heart rate variability (HRV), and refreshed mental acuity.

This chronobiology tool calculates ideal bedtimes if you need to wake up at a specific hour, optimal wake-up times if you plan to fall asleep right now or at a selected time, and specialized Power Nap protocols (20-min Stage 2 motor-learning nap vs 90-min full neurocognitive rejuvenation cycle). Customizable sleep latency (average 14 minutes to fall asleep) and age-tailored total sleep duration recommendations included.