Find useful sleep-cycle bedtimes and wake-up times.
This tool works directly in your browser. Your entries stay on your device.
What it does
Sleep runs in cycles of roughly ninety minutes. Waking at the end of a cycle feels very different from waking in the middle of one. Tell the calculator when you need to be up, when you are going to bed, or that you are going to bed right now, and it gives you the times worth aiming for.
How to use it
- Choose a mode: I need to wake at…, I’m going to bed at…, or I’m going to bed now.
- Enter the time.
- Adjust how many minutes you usually take to fall asleep. Fourteen minutes is a common average, but use your own number if you know it.
- Optionally change the cycle length. Ninety minutes is typical; real cycles run roughly 70 to 110 minutes and vary through the night.
How to read the results
Treat each suggested time as the middle of a window, not an exact minute. If two good times are half an hour apart, going to bed at the earlier one usually makes waking easier.
What it can’t do
It can’t make five hours enough. Total sleep matters far more than where the cycles land, and no timing trick beats going to bed earlier. Most adults need around seven to nine hours. If you regularly wake exhausted after a full night, that is worth raising with a doctor.
- Works with
- A modern desktop browser
- Files included
- Interactive HTML
- Usage & licence
- Check the product description and Terms for permitted use.
