← All Calculators
Sleep Cycle Calculator
Find your optimal bedtime or wake time based on sleep cycles.
How it works
A full sleep cycle lasts ~90 minutes. Waking between cycles helps you feel refreshed. This calculator factors in ~15 minutes to fall asleep and recommends times aligned with complete cycles.
Frequently Asked Questions
How long is a sleep cycle?+
A full sleep cycle lasts about 90 minutes on average and moves through light, deep and REM sleep. Four to six such cycles repeat over the night. This calculator assumes 90-minute cycles.
How much sleep do I need?+
The National Sleep Foundation (NSF) recommends roughly 7 to 9 hours of sleep per night for healthy adults. Individual needs can vary somewhat.
Why do I sometimes wake up groggy?+
Being woken in the middle of deep sleep often causes grogginess (sleep inertia). Waking at the end of a cycle, during a lighter sleep stage, is usually felt as more refreshing.
Why are 15 minutes of falling-asleep time included?+
Most people take about 10 to 20 minutes to fall asleep. The calculator adds roughly 15 minutes so the calculated times are more realistic.
What helps for better sleep?+
Professional bodies such as the American Academy of Sleep Medicine (AASM) recommend consistent sleep times, a dark and cool bedroom, and avoiding caffeine and screens before bed. Seek medical advice for persistent sleep problems.
Are the calculated times medically binding?+
No. The times are guidance based on average cycles. For persistent sleep disturbances, consult a physician or a sleep specialist.
Related Calculators
Alcohol Unit Calculator
Calculate your weekly alcohol consumption in UK units, grams of pure alcohol, and health risk.
Anemia Risk Calculator
Estimate your anemia risk from hemoglobin level, sex, and clinical symptoms.
Anion Gap Calculator
Calculate anion gap and classify metabolic acidosis. Includes albumin correction.
Ankle-Brachial Index (ABI) Calculator
Calculate left, right and overall ABI from four cuff pressures. Screen for peripheral artery disease (PAD).
Background
Calculate Sleep Cycles: Wake Up at the Right Time
6 min