SleepCycle Calculator
Calculate optimal sleep times based on your natural sleep cycles
Recommended Sleep Times
The average human takes 15 minutes to fall asleep. To wake up refreshed at 8:00 AM, you need to go to sleep at one of the following times:
6 Sleep Cycles
9 hours of sleep
5 Sleep Cycles
7.5 hours of sleep
4 Sleep Cycles
6 hours of sleep
3 Sleep Cycles
4.5 hours of sleep
Understanding Sleep Cycles
If you wake up at one of these times, you'll rise in between 90-minute sleep cycles. A good night's sleep consists of 5-6 complete sleep cycles.
Sleep occurs in cycles of approximately 90 minutes each. Each cycle consists of four stages:
- Stage 1: Light sleep (5-10 minutes) - Transition between wakefulness and sleep
- Stage 2: Onset of sleep (10-25 minutes) - Body temperature drops and heart rate slows
- Stage 3: Deep sleep (20-40 minutes) - Most restorative stage, difficult to wake from
- REM sleep (10-60 minutes) - Dreaming stage, brain activity similar to wakefulness
Waking up between cycles (at the end of a cycle) helps you feel more refreshed and alert.
SleepCycle | Advanced Sleep Calculator
Find Your Perfect Sleep Schedule
Our Sleep Calculator helps you find the best time to sleep and wake up so you can feel refreshed and energized. Instead of just aiming for “8 hours,” it considers natural sleep cycles — each lasting about 90 minutes — to help you wake up at the right stage of sleep.
This tool is useful for:
Improving morning energy – wake up at the right time
Avoiding grogginess – prevent waking during deep sleep
Planning naps – know how long to rest without feeling tired afterward
Adjusting for work or school schedules – optimize sleep around commitments
Example cycles:
If you need to wake up at 6:30 AM, the calculator might suggest going to bed at 9:00 PM, 10:30 PM, or 12:00 AM for a full night’s rest.
If you want to fall asleep at 10:00 PM, it will tell you the best wake-up times based on complete cycles.
FAQ – Sleep Calculator
1. How does the sleep calculator work?
It calculates your bedtime or wake-up time based on 90-minute sleep cycles and average time to fall asleep.
2. How many hours of sleep do I really need?
Most adults need 7–9 hours, but quality and timing are just as important as quantity.
3. Can this help with insomnia?
While it’s not a medical cure, it can help you set a consistent schedule that supports healthy sleep habits.
4. Is this based on science?
Yes — it follows research on circadian rhythms and REM sleep cycles.
5. Is it free to use?
Yes — it’s an online tool that works instantly without downloads.