Wake up between sleep cycles, not in the middle of one. Enter a time and get the best bedtimes or wake-up times. Free, no signup.
A full sleep cycle averages about 90 minutes. Waking at the end of one — rather than mid-cycle — tends to feel far less groggy. Aim for 5–6 complete cycles.
No — it’s a simple planning tool based on average cycle length. Everyone’s a little different, so treat the times as a helpful guide.