Bedtime and wake-time calculator
Work back from your alarm, or forward from lights-out.
Go to bed at
Wake up at
That time didn't come through in a form we can read. Enter it as a 24-hour time, like 07:00.
Each option includes the time you said it takes to fall asleep, so these are lights-out and alarm times rather than time asleep.
What a "sleep cycle" means here
Sleep runs in repeating cycles through lighter and deeper stages and REM. Waking at the end of one, rather than out of the middle of deep sleep, is generally the more comfortable place to be woken — which is the entire idea this calculator is built on.
The 90-minute figure everyone quotes is an average. Real cycles run roughly 70 to 120 minutes, differ between people, and lengthen through the night. That's why the cycle length is an input here rather than a hidden constant: if you know yours runs short, use your number and the times move accordingly.
Why it adds time to fall asleep
The times are lights-out and alarm times, not hours asleep. Most people don't fall asleep the moment they get in bed, so the calculator adds that gap — 15 minutes by default — before it starts counting cycles. If you routinely lie awake far longer than that, put your real number in. And if lying awake is the problem rather than the arithmetic, that's one of the things thequestionnaire asks about.
Don't over-trust the precision
This is a schedule aid, not a measurement. Nobody's cycles keep exact time, and hitting a calculated boundary to the minute isn't a thing you can actually do. The useful output is a bedtime range that leaves you enough total sleep — which you can sanity-check againstthe recommended range for your age.