Sleep Cycle

Bedtimes in 90-min cycles. Use the Sleep Cycle below — everything runs in your browser, nothing is uploaded.

How it works

Enter your values in the Sleep Cycle above. Results update instantly and stay on your device.

Formula and source

This tool applies its standard published method. Check the linked source for the exact definition.

Tips

• Double-check units before trusting a result.
• Bookmark the page — its address never changes.

FAQ