Good sleep starts before you close your eyes. This bedtime calculator works backwards from your alarm and shows when to go to bed so you wake up between sleep cycles, not in the middle of one.
The other half is getting to sleep. Your body needs to shift out of the alert mode of the day before it can rest, and that doesn't happen just because the lights are off.
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Cycle length varies from person to person, so treat these times as a guide, not a precise prediction. If falling asleep usually takes you longer than you'd like, the practices below are a good place to start.
Right now
Slow breathing and guided rest give your body a signal that it's safe to slow down. Pick one and do it in bed.
Sleep moves in cycles. Each one passes through light sleep, deep sleep and REM, and on average lasts about 90 minutes. Most people go through four to six cycles a night.
Deep sleep is hardest to wake from, and there's more of it in the first half of the night. REM periods get longer towards morning. The calculator adds your time to fall asleep, then counts back in full cycles from your alarm, so the alarm falls between cycles rather than in the middle of one.
You may have noticed this: you go to bed on time, you're tired, and still you lie awake. The body is ready for sleep, but something keeps it on.
There's a reason this happens. Falling asleep needs your nervous system to shift from the alert, ready-to-act mode of the day into a slower, restful one. Stress, a busy evening or a mind that keeps replaying the day can hold it in alert mode longer. Sleep researchers have found that people whose sleep is easily disrupted by stress are more likely to struggle with falling asleep.
The good news is that this shift can be practised. Slowing your breath and letting your body rest on purpose sends the same signal, night after night.
The 90-minute figure is an average. The first cycle of the night is often shorter, around 70 to 100 minutes, and later ones tend to run 90 to 120 minutes. Most adults take about 10 to 20 minutes to fall asleep.
The American Academy of Sleep Medicine and the Sleep Research Society recommend that adults sleep 7 or more hours a night on a regular basis. Some people need more than 9.
A 2026 systematic review found that people reported longer and better sleep after practising slow breathing before bed, though lab measurements were less clear. A small 2021 study of adults with chronic insomnia found that regular Yoga Nidra practice shortened the time it took them to fall asleep. Promising, but early: more research is needed.
Many REM sleep calculators work the same way: they count 90-minute cycles. None of them can tell exactly when your REM sleep happens. That takes a sleep lab, where brain activity, eye movements and muscle tone are recorded overnight. This calculator aims for the end of a cycle, when sleep is usually lighter.
Adults should sleep 7 or more hours a night on a regular basis. If you use this as a sleep time calculator, aim for 5 or 6 cycles. Four cycles fit neatly but give you only about 6 hours.
Switch the setting to 30 minutes and the bedtimes will move earlier. If falling asleep regularly takes you much longer than that, it's worth talking to a doctor.
Being tired and being ready to sleep aren't the same thing. You can feel exhausted while your nervous system is still switched on: mind busy, body tense. If this sounds familiar, take our nervous system test. One of its results, "Wired and tired", describes exactly this mix.
Take the nervous system test →This calculator gives a general guide based on average sleep cycles, not a medical recommendation. If you often struggle to fall asleep or stay asleep, talk to a doctor.