Sleep Calculator - Wake up refreshed using REM sleep cycle science

Sleep Calculator REM calculates your perfect wake-up and bedtime windows based on 90-minute REM sleep cycles. Most people wake up groggy not because they slept less — but because they woke up in the middle of a sleep cycle. This tool fixes that. 🌙 3 Modes: • Wake Up — enter bedtime, get best wake times • Bedtime — enter wake time, get best bedtimes • Sleep Now — instant calculation from now ✨ Features: • Age-based sleep recommendations • Visual REM cycle diagram • Sleep debt calculat