Sleep Cycle Alarm Calculator
Sleep happens in 90-minute cycles, and waking up at the end of a cycle feels much easier. Pick a mode below: find the best bedtimes for a fixed wake-up time, or find the best wake times if you are going to sleep now.
Choose a Mode
How to use
- Pick one of the two modes at the top.
- For wake-up mode: enter your wake-up time and press "Show Bedtimes". The calculator counts back in 90-minute cycles and adds 15 minutes to fall asleep.
- For sleeping-now mode: choose how soon you will fall asleep and press "Show Wake Times". The calculator counts forward in 90-minute cycles from that point.
- Each result card shows the time, how many sleep cycles it covers, and the total sleep time.
- The card marked "Best" lands in the 7.5 to 9 hour range, which suits most adults.
Tips
- Most adults need 7.5 to 9 hours of sleep per night for good health and focus.
- One sleep cycle lasts about 90 minutes. Completing full cycles avoids waking up groggy.
- The calculator adds 15 minutes for falling asleep, because most people do not fall asleep instantly.
- Keep your wake time consistent every day, even on weekends. A steady rhythm improves sleep quality.
- Avoid bright screens and caffeine in the hour before bed for faster, deeper sleep.