Sleep Calculator
Find your perfect bedtime based on sleep cycles
Wind-down time accounts for Evening Reflection, brushing teeth, etc.
Your optimal bedtimes:
💡 Why these times?
Sleep happens in 90-minute cycles. Waking up between cycles (not during one) helps you feel more refreshed. These times give you complete sleep cycles plus time to fall asleep.
Most people take 10-20 minutes to fall asleep. The recommended option gives you 7.5-8 hours of actual sleep (5-6 complete cycles).
🌙 Make it happen tonight
Set an alarm for 10:00 PM
This is your signal to start winding down
Process your day and let go of stress (5-10 min)
Play Sleep Sounds
Gentle rain or ocean waves to help you drift off
Popular Wake Times & Ideal Bedtimes
Quick reference for common schedules
Wake at 6:00 AM
10:15 PM
Bedtime (7.5 hours, 5 cycles)
Wake at 7:00 AM
11:15 PM
Bedtime (7.5 hours, 5 cycles)
Wake at 8:00 AM
12:15 AM
Bedtime (7.5 hours, 5 cycles)
Or enter your custom wake time above ↑
Want to understand how this works?
Learn why timing matters more than hours, how sleep cycles work, and get answers to questions like "How many hours is 11pm to 7am?"
Read the Complete Sleep Calculator Guide →How Sleep Cycles Work
🔄 The 90-Minute Cycle
Your brain moves through different sleep stages in roughly 90-minute cycles. Each cycle includes light sleep, deep sleep, and REM (dream) sleep. A full night includes 4-6 complete cycles.
⏰ Timing Matters
Waking up at the end of a cycle (during light sleep) feels natural and refreshing. Waking up during deep sleep makes you feel groggy and disoriented. That's why 7.5 hours can feel better than 8 hours.
😴 Fall Asleep Time
Most people take 10-20 minutes to fall asleep. That's why the calculator adds extra time beyond your target sleep duration. If you fall asleep faster or slower, adjust accordingly.
🎯 Individual Variation
Sleep cycles aren't exactly 90 minutes for everyone—they range from 80-120 minutes. Use these times as a starting point, then adjust based on how you feel when you wake up.
Note: This calculator provides general guidance based on average sleep cycle length. Individual needs vary. Consistently getting quality sleep matters more than hitting exact numbers.
Common Sleep Questions
What time should I go to bed to wake up at 7am?
For a 7am wake time, the best bedtimes are 11:15pm (7.5 hours, 5 cycles), 10pm (9 hours, 6 cycles), or 12:45am (6 hours, 4 cycles). These times align with complete 90-minute sleep cycles, so you wake up feeling refreshed instead of groggy.
How many hours of sleep is 11pm to 7am?
11pm to 7am is exactly 8 hours of sleep. However, 8 hours interrupts your sleep cycles (it's 5.3 cycles instead of a complete number). You'll actually feel better with 11:15pm to 7am, which gives you 7.5 hours (exactly 5 complete 90-minute cycles).
Is 6 hours of sleep enough?
6 hours equals exactly 4 complete sleep cycles, so you can wake up feeling okay in the short term. However, most adults need 7-9 hours for optimal health. If you only have 6 hours available, make sure they're high-quality hours by going to bed at the right time to complete 4 full cycles.
Why do I feel groggy after 8 hours of sleep?
You're probably waking up in the middle of a sleep cycle (during deep sleep) rather than at the end. 8 hours equals 5.3 cycles, which means you're interrupting your 6th cycle. Try 7.5 hours (5 complete cycles) or 9 hours (6 complete cycles) instead—you'll likely feel much better.
Should I keep the same bedtime every night?
Your wake time matters more than your bedtime for regulating your body clock. Try to wake up at the same time every day (even weekends) within a 30-minute window. Once your wake time is consistent, your body will naturally feel sleepy at the right bedtime.
What if I can't fall asleep at the calculated time?
Don't force it. If you're lying awake after 20-30 minutes, get up and do something calming (like Evening Reflection or listening to sleep sounds) until you feel sleepy. Forcing yourself to stay in bed when not sleepy creates anxiety around sleep.
How many hours is 10pm to 6am?
10pm to 6am is 8 hours. Like 11pm-7am, this interrupts your natural cycles. For better sleep quality, try 10:15pm to 6am (7.75 hours, nearly 5 complete cycles) or 9pm to 6am (9 hours, 6 complete cycles).
Do naps follow the same cycle pattern?
Yes! This is why 20-minute "power naps" (before deep sleep kicks in) or 90-minute naps (one full cycle) work well, but 45-60 minute naps often leave you groggy—you wake up during deep sleep. Stick to either very short (15-20 min) or one full cycle (90 min).
Optimize your entire sleep routine: