When Should I Go to Sleep?
Enter your wake-up time to find optimal bedtimes based on sleep cycles
Results update automatically as you adjust the time
How to Use Sleep Calculator
- 1 Enter your desired wake-up time
- 2 See recommended bedtimes for 3-6 sleep cycles
- 3 Choose a bedtime that fits your schedule
- 4 Fall asleep 10-15 minutes after going to bed
What You Get
Calculates optimal bedtimes based on 90-minute sleep cycles. Waking up between cycles helps you feel refreshed instead of groggy.
Input: Wake up at 7:00 AM
Output: 21:46 (6 cycles), 23:16 (5 cycles), 00:46 (4 cycles)
Input: Wake up at 6:30 AM
Output: 21:16 (6 cycles), 22:46 (5 cycles), 00:16 (4 cycles)
What time should I go to bed if I wake up at 7am?
To wake at 7:00 AM, go to bed at 9:30 PM (6 cycles), 11:00 PM (5 cycles), or 12:30 AM (4 cycles). Add 14 minutes for falling asleep.
What is a sleep cycle and how long does it last?
A sleep cycle is about 90 minutes. It includes light sleep, deep sleep, and REM sleep. Most adults complete 4-6 cycles per night.
Why do I feel tired after 8 hours of sleep?
You may be waking mid-cycle during deep sleep. Try 7.5 hours (5 cycles) or 9 hours (6 cycles) to wake at the end of a cycle feeling refreshed.
How long does it take to fall asleep?
On average 10-15 minutes. Our calculator adds 14 minutes to recommended bedtimes. If you take longer, adjust accordingly.
How many hours of sleep do I need?
Most adults need 7-9 hours (5-6 cycles). Teenagers need 8-10 hours. Sleep quality matters as much as duration.
Is the 90-minute sleep cycle accurate for everyone?
Individual cycles may vary by 10-20 minutes. The 90-minute average is scientifically established and works as a reliable starting point.
How do I calculate bedtime for any wake-up time?
Count backwards in 90-minute intervals from your wake time. Subtract 6 cycles (9 hours), 5 cycles (7.5 hours), or 4 cycles (6 hours), then add 14 minutes.
Does the calculator account for time to fall asleep?
Yes. We add 14 minutes to the bedtimes shown, based on average sleep onset time. Adjust if you fall asleep faster or slower.
All calculations happen locally in your browser. No data is sent to any server.