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90 Minute Sleep Cycle Calculator

Created by Luciano Miño
Reviewed by Komal Rafay
Based on research by
Hirshkowitz M, Whiton K, Albert SM, Alessi C, Bruni O, DonCarlos L, Hazen N, Herman J, Katz ES, Kheirandish-Gozal L, Neubauer DN, O'Donnell AE, Ohayon M, Peever J, Rawding R, Sachdeva RC, Setters B, Vitiello MV, Ware JC, Adams Hillard PJ. National Sleep Foundation's sleep time duration recommendations: methodology and results summary.; Sleep Health; March 2015See 1 more source
Shen, X., Wu, Y. & Zhang, D. Nighttime sleep duration, 24-hour sleep duration and risk of all-cause mortality among adults: a meta-analysis of prospective cohort studies; Scientific Reports; February 2016
Last updated: Jan 18, 2024


Our 90 minute sleep cycle calculator is the perfect tool to know how long you should sleep to wake up at the end of a sleep cycle.

This tool takes into account how long you take to fall asleep and your regular wake-up time. We've paired this calculator with a short text, describing:

  • The benefits of a regular sleep schedule;
  • What sleep cycles are or 90-minute sleep blocks are;
  • Risks of sleep deprivation;
  • The best times to sleep and wake up based on your needs.

What are the 90 minutes of sleep blocks?

While we are sleeping, our bodies go through sleep cycles divided into four stages:

  • Light sleep stages (N1, N2): your body slowly starts to relax, and you can easily wake up during this stage.
  • Deep sleep stage (N3) : also known as slow wave sleep.It isn't easy to wake someone up during this stage. During this phase, the body repairs and regrows tissues, and muscle growth occurs.
  • Rapid eye movement, REM, sleep stage (R): brain activity spikes and dreams occur. Your body becomes paralyzed except for your eyes which remain closed but move quickly (here's where REM comes from) and the muscles that control breathing.

These cycles last 90 minutes on average and a good night's rest consists of 5-6 of these cycles.

When you wake up in the middle of a cycle, you are more likely to feel groggy and not rested enough. That's why it's important to wake up when the cycle ends, where sleep is the lightest.

How many hours of sleep do I need?

Adults need between 7-9 hours of sleep, and teens between 8-10. Children need progressively fewer hours of sleep as they grow up. According to the Centers for Disease Control and Prevention (CDC) less than seven hours per night is not enough sleep.

💡 Our 90-minute sleep cycle calculator can tell you precisely how many sleep cycles per night you can fit in according to your schedule ⌚

Here's the detailed breakdown according to the National Sleep Foundation:

Age range

Hours of sleep

Newborn to 3 months old

14-17

4 To 11 months old

12-15

1 To 2 years old

11-14

3 To 5 years old

10-13

6 To 13 years old

9-11

14 To 17 years old

8-10

Young adults (18 to 25 years old)

7-9

Adults (26 to 64 years old)

7-9

Older adults (65+)

7-8

Risks of sleep deprivation

Sleep deprivation can cause a lot of harmful and unwanted effects on your body, such as:

  • Drowsiness;
  • Fatigue;
  • Irritability;
  • Increased risk of stroke, coronary heart disease, hypertension, obesity, and type 2 diabetes;

Our 90-minute sleep cycle calculator also includes the increase in mortality risk associated with your sleep hours.

🙋 Still wondering what the best time to sleep and wake up are? Plug in the amount of time you need to fall asleep and your desired wake-up time into our 90-minute sleep cycle calculator. It will automatically find the best combination of sleeping times and the number of cycles that can fit within those hours.

Other sleep tools 💤

If you want to learn more about the stages of sleep and what you can do to improve sleep, take a look at these similar tools:

FAQ

How many sleep cycles do you need per night?

5, 90-minute cycles. Each cycle lasts 90 minutes on average, and the recommended sleep time for adults is 7-8 hours. You can fit five complete 90-minute cycles during that time. If you sleep more or less, you risk interrupting these cycles and not resting well enough.

How do I sleep better?

Here are a few tips you can take to sleep better:

  1. Go to bed at the same hour every night and wake up at the same time every morning.
  2. Avoid large meals when close to bedtime.
  3. Make sure your room is dark and quiet.
  4. Exercise during the day.
  5. Do breathing exercises to reduce stress.
Luciano Miño
What time should I go to sleep?
Time to fall asleep
minutes
Waking up time
7:00 AM

To wake up at the end of a sleep cycle, go to sleep at:
  - 9:45 PM (6 cycles, 9h of sleep) - recommended for long-sleepers,
  - 11:15 PM (5 cycles, 7h30m of sleep) - recommended for average-sleepers,
  - 12:45 AM (4 cycles, 6h of sleep) - recommended for short-sleepers,
  - 2:15 AM (3 cycles, 4h30m of sleep),
  - 3:45 AM (2 cycles, 3h of sleep),
  - 5:15 AM (1 cycle, 1h30m of sleep).

If you go to sleep NOW, you should wake up at:
  - 3:10 AM (6 cycles, 9h of sleep) - recommended for long-sleepers,
  - 1:40 AM (5 cycles, 7h30m of sleep) - recommended for average-sleepers,
  - 12:10 AM (4 cycles, 6h of sleep) - recommended for short-sleepers,
  - 10:40 PM (3 cycles, 4h30m of sleep),
  - 9:10 PM (2 cycles, 3h of sleep),
  - 7:40 PM (1 cycle, 1h30m of sleep).
How dangerous is my sleep routine?
Night-time sleep duration
7 hours
Increase in mortality risk
0
%
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