Is 8 Hours of Sleep Enough?
Eight hours of sleep is enough for almost all adults, and it sits in the middle of the 7 to 9 hours the National Sleep Foundation recommends. It is still on the short side for teenagers, who need 8 to 10 hours.
Bedtimes for 8 hours of sleep
Each bedtime includes 15 minutes to fall asleep.
Enough for adults?
Yes, for most adults
Sleep cycles
5.3
Sleep debt per week vs. 7 h
None
| To wake up at | Go to bed at |
|---|---|
| 5:30 AM | 9:15 PM |
| 6:00 AM | 9:45 PM |
| 6:30 AM | 10:15 PM |
| 7:00 AM | 10:45 PM |
| 7:30 AM | 11:15 PM |
| 8:00 AM | 11:45 PM |
Want a different wake-up time? The sleep calculator finds bedtimes that end on a full sleep cycle.
What the research says about 8 hours of sleep
Eight hours is 5.3 sleep cycles. If you wake up groggy after 8 hours, aiming for 7.5 or 9 hours, five or six full cycles, often helps, because the alarm then lands in light sleep.
How much sleep you need by age
These are the National Sleep Foundation's recommended ranges.
| Age | Hours per night |
|---|---|
| School-age children (6–13) | 9–11 |
| Teenagers (14–17) | 8–10 |
| Adults (18–64) | 7–9 |
| Older adults (65+) | 7–8 |
Other sleep lengths
- Is 3 hours of sleep enough?
- Is 4 hours of sleep enough?
- Is 5 hours of sleep enough?
- Is 6 hours of sleep enough?
- Is 6.5 hours of sleep enough?
- Is 7 hours of sleep enough?
- Is 9 hours of sleep enough?
Running short most nights? The sleep debt calculator shows how much you owe and how long it takes to pay back.
More free sleep tools
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Sleep Debt Calculator
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REM Sleep Calculator
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Jet Lag Calculator
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Sleep Efficiency Calculator
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Sleep Schedule Calculator
A day-by-day plan to fix your sleep schedule or adjust to daylight saving time.
Caffeine Calculator
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Chronotype Quiz
Five questions to find out if you are a morning lark or a night owl.
Frequently asked questions
Is 8 hours of sleep enough?
Eight hours of sleep is enough for almost all adults, and it sits in the middle of the 7 to 9 hours the National Sleep Foundation recommends. It is still on the short side for teenagers, who need 8 to 10 hours.
How many sleep cycles is 8 hours of sleep?
About 5.3 cycles of 90 minutes. Because that isn't a whole number, waking at 8 hours often interrupts a cycle; 7 h 30 min or 9 h usually feels better.
What time should I go to bed to get 8 hours of sleep?
Count back 8 hours and 15 minutes from your alarm. To wake at 7:00 AM, go to bed at 10:45 PM.