Counting forward from 8:00 PM
If you get into bed at 8:00 PM and fall asleep about 15 minutes later, your first sleep cycle starts at 8:15 PM. With cycles of roughly 90 minutes, they end at:
- 2:15 AM (02:15) after four cycles, or 6 hours asleep;
- 3:45 AM (03:45) after five cycles, or 7.5 hours;
- 5:15 AM (05:15) after six cycles, or 9 hours.
All three times fall in the early hours of the next morning, which is why an 8:00 PM bedtime mainly suits very early starts.
Which wake-up time fits an 8 PM bedtime?
3:45 AM gives 7.5 hours of sleep, meeting the recommendation that adults sleep at least 7 hours. It suits jobs that start around 5:00 AM, such as bakeries, early transport, deliveries and hospital early shifts.
5:15 AM gives 9 hours. It is a good fit if you start at 6:00 or 7:00 AM and want plenty of rest, or if you are recovering from several short nights.
2:15 AM gives only 6 hours and is rarely a good choice. It only makes sense for an occasional very early flight or drive.
If you take more or less than 15 minutes to fall asleep
The times above allow 15 minutes to fall asleep. Early in the evening, many people take longer, especially in their first week on an early shift. Use the row that matches you; the highlighted row matches the answer at the top of this page.
| Fall asleep in | 9 h | 7.5 h | 6 h |
|---|---|---|---|
| 5 min | 5:05 AM05:05 | 3:35 AM03:35 | 2:05 AM02:05 |
| 10 min | 5:10 AM05:10 | 3:40 AM03:40 | 2:10 AM02:10 |
| 15 min | 5:15 AM05:15 | 3:45 AM03:45 | 2:15 AM02:15 |
| 20 min | 5:20 AM05:20 | 3:50 AM03:50 | 2:20 AM02:20 |
| 30 min | 5:30 AM05:30 | 4:00 AM04:00 | 2:30 AM02:30 |
Getting used to an 8 PM bedtime
If you normally go to bed around 11:00 PM, you probably won’t fall asleep at 8:00 PM on the first night. Move your bedtime and alarm earlier by 30 minutes every day or two in the week before early shifts start, and get bright light soon after you wake.
Keep the last hour before bed calm and dim, eat your main meal a few hours before bedtime, and avoid caffeine after late morning. Ask others in your home to keep noise down, or use earplugs or a fan.
Is 8 PM a good bedtime for children?
For many school-age children, yes. Children aged 6 to 13 need 9–11 hours of sleep. Asleep by about 8:15 PM, a child would get 9 hours by 5:15 AM and 10.5 hours by 6:45 AM. Children don’t need to wake at the end of a cycle in the same way; what matters most is getting enough sleep. See sleep needs by age for every age group.
More answers
- Wake-up time if you sleep at 8:30 PMNearby answer
- Wake-up time if you sleep at 9 PMNearby answer
- Bedtime for a 4 AM wake-upRelated answer
- Bedtime for a 4:15 AM wake-upRelated answer
- Bedtime for a 4:30 AM wake-upRelated answer
- Bedtime for a 4:45 AM wake-upRelated answer
Frequently asked questions
Is 8 PM too early to go to bed?
Not if you have an early start. Allowing 15 minutes to fall asleep, an 8:00 PM bedtime gives 7.5 hours with a 3:45 AM (03:45) alarm, or 9 hours with a 5:15 AM (05:15) alarm.
How much sleep do I get from 8 PM to 5 AM?
About 8 hours 45 minutes, if you fall asleep by 8:15 PM. That is plenty for most adults, although 5:15 AM lines up more closely with the end of a cycle.
Why do I wake up in the middle of the night after an early bedtime?
If you go to bed much earlier than usual, your body may not need the full night yet, or your body clock may not be ready for sleep. Moving bedtime earlier gradually, and keeping the room dark and quiet, usually helps.
Related calculators
Wake-up time calculator
Going to bed now or at a set time? Find wake-up times that land at the end of a cycle.
Bedtime calculator
Enter any wake-up time to see bedtimes that let you wake between sleep cycles.
Nap calculator
Plan a 10-, 20- or 90-minute nap and see when to set your alarm.
Sleep debt calculator
Add up the last seven nights and see how far you are from your sleep target.
Sources
- National Institute of Neurological Disorders and Stroke. Brain Basics: Understanding Sleep.
- National Heart, Lung, and Blood Institute. How Sleep Works.
- Watson NF, et al. Recommended Amount of Sleep for a Healthy Adult: A Joint Consensus Statement of the American Academy of Sleep Medicine and Sleep Research Society. Journal of Clinical Sleep Medicine, 2015;11(6):591–592. doi:10.5664/jcsm.4758.
- Centers for Disease Control and Prevention. About Sleep.
When to seek help
Talk to a doctor if you:
- regularly take longer than 30 minutes to fall asleep, or wake in the night and can’t get back to sleep;
- snore loudly, or someone notices you gasp or stop breathing while asleep;
- feel very sleepy during the day, especially while driving or working, despite enough time in bed.