SleepCycle: Sleep Calculator

SleepCycle Calculator helps you find the ideal time to go to sleep or wake up — based on real sleep science. Built around the 90-minute sleep cycle model, the app calculates optimal bedtimes and wake-up windows so you always rise at the lightest stage of sleep, feeling alert and refreshed. WHETHER YOU SET A WAKE TIME OR SLEEP NOW • Wake-Up Mode: Enter your desired wake-up time and the app calculates 4–6 ideal bedtimes working backwards in 90-minute cycles, plus a 14-minute fall-asleep buffer. • Sleep Now Mode: Tap "Sleep Now" and the app instantly calculates your best wake-up times based on the current time. BUILT-IN SMART ALARM • Tap any suggested time to set it as your alarm instantly. • Choose from 6 soothing alarm sounds: Gentle Bells, Forest Birds, Ocean Waves, Digital Beep, Soft Chime, and Cosmic Hum. • Preview sounds before selecting. • Dismiss or snooze (9 minutes) when the alarm fires. • Push notifications ensure your alarm fires even when the app is in the background. SLEEP HISTORY & TRACKING • Every dismissed alarm automatically logs a sleep session — bedtime, wake time, duration, cycle count, and quality rating. • View your sleep history on an interactive calendar with color-coded indicators. • Track 7-day and 30-day sleep averages, your best night, and total nights logged. • Weekly bar chart shows sleep duration at a glance. SLEEP SCIENCE EDUCATION • Learn what a sleep cycle really is and why timing matters. • Explore the 4 sleep stages (N1, N2, N3, REM) with durations and biological functions. • Understand the 90-minute rule and the 14-minute sleep onset latency formula used by this app. • Science-backed sleep tips on room temperature, blue light, caffeine, and more. • 7 tappable references to peer-reviewed sources including the Sleep Foundation, NIH, and Harvard Health. BEAUTIFUL DESIGN • Deep indigo night-sky aesthetic inspired by Apple's bedtime design language. • Color-coded quality labels: Optimal, Great, Good, and Light for each sleep option. • Smooth animations, haptic feedback, and a breathing moon animation for a calming experience. SleepCycle Calculator is perfect for anyone who wants to stop waking up groggy and start waking up energized — backed by science, not guesswork. Note: A medical disclaimer is included in the app. This app is not intended to diagnose or treat sleep disorders. For serious sleep concerns, please consult a healthcare professional. PREMIUM ACCESS Try SleepCycle Pro free for 14 days. After the trial, unlock full lifetime access for a one-time purchase of $19.99 — no subscription, ever. Premium features include personalized sleep insights, full history tracking, and all future updates.