Sleep Calculator
Sleep in complete 90-minute cycles for your age, and get a pillow tip for your position.
How it works
We sleep in cycles of about 90 minutes, moving through light, deep and REM sleep. Waking in the middle of a cycle is what leaves you groggy; waking between cycles helps you feel refreshed.
The calculator adds the time you take to fall asleep, and highlights the number of cycles that suits your age group.
What is a sleep calculator?
A sleep calculator is a tool that calculates the optimal time to go to bed and get up to ensure you wake up at the end of a sleep cycle. You set the time you want to wake up (or go to bed) and select your age group, and it counts down or up in 90-minute increments. This leaves you with a short list of times that will help you get a good night’s sleep without waking up feeling groggy.
How to use the Sleep calculator
- Choose your goal. Set a wake-up time, go to bed right now, or go to bed at a specific time.
- Add your details. Pick your age group, sleep position, and how long you take to fall asleep, so the result is tailored to you.
- Read your best times. Each option shows the cycles and hours of sleep it gives, with the ideal number for your age highlighted, plus a pillow tip for your position.
How sleep cycles work
Your body doesn’t sleep at the same depth throughout the night. It cycles through light sleep, deep sleep and REM (dream) sleep in a repeating pattern of approximately 90 minutes. If you wake up during deep sleep you feel heavy and disoriented; if you wake up at the end of a cycle, getting up is much easier.
Recommended hours of sleep by age
How much sleep you need changes a lot through life. These are the general ranges most health guidelines agree on:
| Age group | Age range | Hours / night |
|---|---|---|
| Newborn | 0-3 months | |
| Infant | 4-12 months | |
| Toddler | 1-2 years | |
| Preschool | 3-5 years | |
| School Age | 6-12 years | |
| Teen | 13-18 years | |
| Adult | 18-60 years | |
| Older Adult | 61-64 years | |
| Senior | 65+ years |
Quality is as important as quantity and finishing a complete cycle can make you feel better than a longer, incomplete night.
Small changes that help you fall asleep faster
Go to bed and get up at the same time each day, even on weekends. Turn down the lights and screens an hour before sleep. Keep bedroom cool and dark. Not to mention, ensure your pillow is appropriate for your sleeping position as the incorrect pillow will have you rolling around and waking up out of a deep sleep.
A stiff neck may be due to the pillow you are using if you tend to wake up with it. See our guides to the best pillows for side sleepers, the best pillows for neck pain, or learn how to choose a pillow.
Frequently asked questions
This depends on your age. Most adults require 7-9 hours, teens require 8-10 hours, and school-age children require 9-12 hours. For each age group, see the table above.
If your alarm is set to wake you from a deep sleep, you may feel groggy even after a long night’s sleep. This calculator indicates that waking at the end of a cycle is typically easier.
Most adults need to sleep for 5 to 6 cycles, which is about 8:45 PM or 10:15 PM to 6:00 AM. Enter 6:00 AM above to see the exact bedtimes.
Yes. Children and teens require significantly more sleep than adults, and sleep requirements change with age. When you select your age group, the appropriate number of cycles will be highlighted.
Yes. You can specify the time you typically spend to fall asleep, and it is incorporated into the times displayed.
Yes. If the pillow doesn’t provide support for your neck in your sleep position, you may shift, wake up and fall out of deep sleep. The proper height and firmness will keep you comfortable throughout each cycle.
This tool and guide are for general information and are not medical advice. If you have ongoing sleep problems, please speak with a qualified healthcare professional.