Enter the time you want to wake up to see the best times to go to bed, or your bedtime to see when to set your alarm, in whole 90-minute sleep cycles plus the time it takes to fall asleep, with the sleep recommended for your age.
Like 6:30 am, 23:00 or 10.45pm
Cycle length, time to fall asleep and clock
min
About 90 minutes on average; 60 to 120 for most people
min
About 15 minutes on average
To wake up at 7:00 am between cycles, go to bed at one of these times:
9:45 pm6 cycles · 9 h of sleep · recommended
11:15 pm5 cycles · 7 h 30 min of sleep · recommended
12:45 am4 cycles · 6 h of sleep
2:15 am3 cycles · 4 h 30 min of sleep
Adult (26–64 years): 7–9 hours of sleep a night is recommended, which is 5 or 6 cycles of 90 minutes.
Each time includes 15 minutes to fall asleep. Waking at the end of a cycle, in light sleep, usually feels easier than waking from deep sleep.
Cycles vary from person to person and through the night. If you're often tired however long you sleep, talk to a doctor.
How to use the sleep cycle calculator
Choose whether you want to wake up at a set time, go to bed at a set time, or sleep now.
Enter the time, like 6:30 am or 23:00, and pick your age group.
Pick one of the times shown; the highlighted ones give the hours of sleep recommended for your age.
Change the cycle length or the time you take to fall asleep under the extra settings if you know yours.
Worked example
To wake at 7:00 am, go to bed at 9:45 pm for six cycles (9 hours of sleep) or 11:15 pm for five (7.5 hours); each includes 15 minutes to fall asleep. Going to bed at 12:45 am gives four cycles, 6 hours, below the 7 hours adults need. Going to bed at 11:00 pm, set the alarm for 6:45 am (five cycles) or 8:15 am (six).
Preschool (3–5) 10–13 hours; school age (6–13) 9–11; teenagers (14–17) 8–10
Adults (18–64) 7–9 hours; older adults (65+) 7–8
Sources: National Sleep Foundation sleep duration recommendations (Hirshkowitz et al., Sleep Health, 2015), Sleep Foundation on sleep cycles and time to fall asleep. General information, not medical advice. Everything runs in your browser.
Frequently asked questions
How does a sleep cycle calculator work?
Sleep comes in cycles of light, deep and REM sleep that last about 90 minutes each. The calculator counts back (or forward) whole cycles from your wake-up time, and adds the time it usually takes to fall asleep, about 15 minutes, so the alarm goes off at the end of a cycle rather than in the middle of deep sleep.
What time should I go to bed to wake up at 6 am?
At 8:45 pm for six cycles (9 hours of sleep) or 10:15 pm for five cycles (7.5 hours), allowing 15 minutes to fall asleep. Four cycles, 6 hours, would mean going to bed at 11:45 pm, which is less than the 7 hours most adults need.
How much sleep do I need?
The National Sleep Foundation recommends 7–9 hours for adults aged 18–64 and 7–8 hours from 65, 8–10 hours for teenagers, 9–11 for children aged 6–13, 10–13 for ages 3–5, 11–14 for toddlers, 12–15 for babies of 4–11 months and 14–17 for newborns.
How long is a sleep cycle?
About 90 minutes on average, but it varies from person to person and through the night: cycles early in the night have more deep sleep and later ones more REM sleep. If you know yours is shorter or longer, change the cycle length in the calculator.
Why wake up at the end of a cycle?
At the end of a cycle you're in light sleep, and waking then usually feels easier than being woken from deep sleep, when grogginess (sleep inertia) is stronger. Getting enough sleep overall matters more than the exact minute.
What if it takes me longer to fall asleep?
Change the time to fall asleep in the calculator, for example to 30 minutes. If it regularly takes you much longer, or you feel tired however long you sleep, talk to a doctor.
