To wake up refreshed, sleep a whole number of sleep cycles of about 90 minutes, and add the time it takes you to fall asleep (about 15 minutes). For example, to wake up at 7 AM, go to bed at 11:15 PM (5 cycles, 7.5 hours of sleep) or at 9:45 PM (6 cycles, 9 hours).
This calculator is offered by ChakraDuo. It is free, with no sign-up, and works on a computer as well as on a phone.
The times below include 15 minutes to fall asleep. For most adults, 5 cycles (7.5 hours of sleep) are a good benchmark.
| Wake up at | 6 cycles (9 h) | 5 cycles (7.5 h) | 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 |
A night is made of 4 to 6 cycles in a row. Each cycle lasts about 90 minutes and goes through three stages:
Early in the night, deep sleep takes up a lot of room. As the hours go by, it shrinks, and dreams last longer. That is what the chart shows: the waves are deeper at first and lighter toward morning.
Why aim for the end of a cycle? Between two cycles, sleep is light. Waking up at that moment feels gentle. Waking up in the middle of deep sleep, on the other hand, leaves you groggy, sometimes for half an hour: this is called sleep inertia.
Sleep experts generally recommend:
| Age | Recommended sleep per night |
|---|---|
| Teenagers (14-17) | 8 to 10 hours |
| Adults (18-64) | 7 to 9 hours |
| Over 65 | 7 to 8 hours |
So 5 cycles (7.5 hours) suit most adults. If you often wake up before your alarm, feeling rested, your cycles may be a little shorter: try going to bed 15 minutes later.
Bedtime is not everything: the 30 minutes before it matter a lot. A few simple ideas:
A cycle lasts 90 minutes on average, but it varies from person to person (70 to 120 minutes), and even from night to night. The times from this calculator are guidelines, not a rule. Listen to your body: if you feel sleepy, go to bed. If tiredness, insomnia or waking up at night lasts for several weeks, talk to a doctor. This calculator does not replace medical advice.
Sleep also shapes your energy during the day, and so your chakras. To find out which ones need your attention, the ChakraDuo test gives you a map of your 7 chakras and a step-by-step action plan.
Start from your wake-up time, then count back in 90-minute steps (one cycle) and subtract the time it takes you to fall asleep, about 15 minutes. To wake up at 7 AM after 5 cycles: 7 AM minus 7.5 hours, minus 15 minutes, gives a bedtime of 11:15 PM. The calculator does it for you.
About 90 minutes on average in adults, ranging from 70 to 120 minutes depending on the person and the night.
Go to bed at 10:15 PM for 5 cycles (7.5 hours of sleep), or at 8:45 PM for 6 cycles (9 hours). These times include 15 minutes to fall asleep.
Set your alarm for 7:45 AM for 5 cycles (7.5 hours of sleep), or for 6:15 AM for 4 cycles (6 hours). These times include 15 minutes to fall asleep.
Because the alarm may have gone off in the middle of deep sleep. Sleeping a little less but waking up at the end of a cycle often makes waking up easier.
A short nap of 10 to 20 minutes refreshes you without reaching deep sleep. A 90-minute nap makes one full cycle. In between, waking up is often harder.
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