Sleep Calculator

How the sleep calculator works

Sleep runs in roughly 90-minute cycles, and waking at the end of a cycle feels far easier than being pulled out of deep sleep midway through one. Enter the time you need to wake up and this calculator counts back in 90-minute blocks — plus about 15 minutes to fall asleep — to suggest the best times to go to bed. Aim for one of them and you're more likely to wake clear-headed.

Still struggling to sleep?

If falling or staying asleep is a regular battle, timing is only part of the picture. Our Sleep & Insomnia guides cover the calm, evidence-based reset behind better nights — from a 14-day plan to shift work, menopause and a racing mind at 2 a.m.