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 disorde