How many sleep cycles do you need?
Most adults aim for 5 or 6 cycles a night, which is 7.5 to 9 hours at about 90 minutes a cycle. Add about 15 minutes to fall asleep. To wake at 7:00 am, that means bed at 11:15 pm or 9:45 pm.
Updated 21 October 2026. Sources named on the page.
- Cycles and hours side by side
- Bedtimes for 6:00 and 7:00 am wake times
- Wake times for common bedtimes
- Why cycle length is only a rule of thumb
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Your own times
Choose a wake time or a bedtime and get times that fit whole cycles.
Cycles, hours and times
Bedtime = wake time minus the cycles (90 minutes each) minus about 15 minutes to fall asleep.
Cycles and hours
| Cycles | Hours of sleep |
|---|---|
| 4 | 6 |
| 5 | 7.5 |
| 6 | 9 |
Bedtime for a wake time
| Wake time | 6 cycles | 5 cycles | 4 cycles |
|---|---|---|---|
| 6:00 am | 8:45 pm | 10:15 pm | 11:45 pm |
| 7:00 am | 9:45 pm | 11:15 pm | 12:45 am |
Wake time for a bedtime
| Bedtime | 6 cycles | 5 cycles | 4 cycles |
|---|---|---|---|
| 10:30 pm | 7:45 am | 6:15 am | 4:45 am |
| 11:00 pm | 8:15 am | 6:45 am | 5:15 am |
Sources: The 90 minute cycle and 15 minutes to fall asleep are commonly used rules of thumb, not measurements of any person; Sleep Health Foundation (Australia): adults generally need 7 to 9 hours
Figures and sources checked 21 October 2026. General information, not medical advice.
What a cycle is
Sleep moves through lighter and deeper stages and back again. One loop is a cycle, often taken as about 90 minutes. It varies from person to person and from night to night, and changes through the night.
Why aim for whole cycles
The idea is that waking at the end of a cycle can feel easier than waking in the middle of deep sleep. It is a rule of thumb, and regular times and enough total sleep matter more than an exact minute.
How to use the table
Pick the row for your wake time, then choose the bedtime for 5 or 6 cycles. If you fall asleep faster or slower than 15 minutes, shift the time to suit.
When to see a doctor
If you are often tired, snore loudly, stop breathing in your sleep or sleep badly for weeks, talk to a doctor. This is not medical advice.
Questions
How long is a sleep cycle?
It is often taken as about 90 minutes, but it varies between people and through the night.
How many cycles is 8 hours?
About 5.3. Five cycles is 7.5 hours and six is 9 hours.
Is 4 cycles enough?
Four cycles is 6 hours, which is below what most adults need on a regular basis. It is shown for nights when you have no choice.
Do naps count as cycles?
A short nap is not a full cycle. Naps are separate from your main night's sleep.
Keep going
Track your sleep habit
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