Sleep Calculator: When to Go to Bed and Wake Up
Find the best bedtime for when you need to wake up, or the best wake-up time for when you go to bed. Times line up with 90-minute sleep cycles, so you wake between cycles instead of in deep sleep.
Your sleep
Go to bed at one of these times
Enter a time to see your best options.
How the sleep calculator works
Through the night you move through sleep cycles of light sleep, deep sleep and REM (dreaming) sleep. Each cycle averages about 90 minutes, and most people go through 4 to 6 of them a night. Deep sleep is concentrated early in the night and REM periods get longer toward morning.
The calculator counts back (or forward) in whole cycles and adds the time it takes you to fall asleep, 15 minutes by default. Choosing a time that ends a cycle means your alarm is more likely to catch you in light sleep, so you're less likely to wake up groggy.
Bedtimes for common wake-up times
Using 90-minute cycles and 15 minutes to fall asleep. Six cycles is 9 hours of sleep, five is 7.5 hours and four is 6 hours.
| Wake up at | Bed for 6 cycles (9 h) | Bed for 5 cycles (7.5 h) | Bed for 4 cycles (6 h) |
|---|---|---|---|
| 5:00 AM | 7:45 PM | 9:15 PM | 10:45 PM |
| 5:30 AM | 8:15 PM | 9:45 PM | 11:15 PM |
| 6:00 AM | 8:45 PM | 10:15 PM | 11:45 PM |
| 6:30 AM | 9:15 PM | 10:45 PM | 12:15 AM |
| 7:00 AM | 9:45 PM | 11:15 PM | 12:45 AM |
| 7:30 AM | 10:15 PM | 11:45 PM | 1:15 AM |
| 8:00 AM | 10:45 PM | 12:15 AM | 1:45 AM |
| 8:30 AM | 11:15 PM | 12:45 AM | 2:15 AM |
| 9:00 AM | 11:45 PM | 1:15 AM | 2:45 AM |
How much sleep do you need?
Recommended hours of sleep by age, from the U.S. Centers for Disease Control and Prevention (CDC):
| Age | Recommended sleep per day |
|---|---|
| Newborn (0–3 months) | 14–17 hours |
| Infant (4–12 months) | 12–16 hours, including naps |
| Toddler (1–2 years) | 11–14 hours, including naps |
| Preschool (3–5 years) | 10–13 hours, including naps |
| School age (6–12 years) | 9–12 hours |
| Teen (13–17 years) | 8–10 hours |
| Adult (18–60 years) | 7 or more hours |
| Adult (61–64 years) | 7–9 hours |
| Adult (65 and older) | 7–8 hours |
Keep in mind
Cycle lengths vary from person to person and from night to night, so treat these times as a guide rather than an exact science. Getting enough total sleep on a regular schedule matters more than hitting the end of a cycle. If you often feel tired even after enough sleep, snore loudly, or struggle to fall or stay asleep, talk to a doctor. This calculator isn't medical advice.
Frequently asked questions
What time should I go to bed if I wake up at 6 AM?
To wake up at 6:00 AM at the end of a sleep cycle, go to bed at 8:45 PM (6 cycles, 9 hours of sleep) or 10:15 PM (5 cycles, 7.5 hours). That allows about 15 minutes to fall asleep. 11:45 PM gives 4 cycles (6 hours), which is less than most adults need.
How many sleep cycles do I need?
Most adults need 5 or 6 cycles a night, which is 7.5 to 9 hours. The CDC recommends at least 7 hours for adults aged 18 to 60, 8 to 10 hours for teens, and 9 to 12 hours for children aged 6 to 12.
Why does the calculator use 90 minutes?
A full sleep cycle, through light sleep, deep sleep and REM, averages about 90 minutes in adults, though it can run from roughly 70 to 120 minutes. If you know your cycles are shorter or longer, change the cycle length setting.
Why wake up at the end of a cycle?
Waking from deep sleep in the middle of a cycle can leave you groggy, an effect called sleep inertia. Waking near the end of a cycle, when sleep is lighter, often feels easier. Total sleep time still matters most.
How long does it take to fall asleep?
A typical healthy adult falls asleep in about 10 to 20 minutes. The calculator adds 15 minutes by default, and you can change it.
Sources: CDC, About Sleep (recommended hours by age); NIH StatPearls, Physiology of Sleep Stages (cycle length and number of cycles); Sleep Foundation, Sleep Latency (time to fall asleep).
Related: Age calculator · Time duration calculator · Hours calculator · Calorie calculator