Sleep Cycle Calculator
Table of contents
What's a sleep cycle? – How long is a sleep cycle?What are the sleep cycle stages?Using the sleep cycle calculatorMore sleep calculators!FAQsThis sleep cycle calculator will help you find the best time to sleep and wake up to achieve a complete number of sleep cycles to feel well-rested throughout the day.
Quality sleep is essential to good health, and understanding the dynamics of sleep cycles is an easy way that can help improve your sleep time. Sleep cycles comprise 90-minute intervals where you progress through the different stages of sleep, from light to REM sleep.
If you'd like to learn more about this subject, then you might want to keep reading to find out:
- Exactly what a sleep cycle is;
- How long a sleep cycle is;
- What the sleep cycle stages are;
- How to calculate the best time to sleep and wake up; and
- How to calculate a sleep cycle using this tool.
Let's dive deep into the Zzz's! 💤
What's a sleep cycle? – How long is a sleep cycle?
Going to bed is not only about putting on your pj's, lying down, and closing your eyes until you wake up the following day. While we're sleeping, our bodies and minds rest and regenerate. To do so, we go through 90-minute-long sleep cycles, repeated throughout the night.
Each sleep cycle has 4 different stages of sleep, and the time required to complete these 4 stages is known as the sleep cycle. During each cycle, we go from light to deep sleep, then back to light sleep, and finally enter a dream state known as the REM cycle.
💡 Although 90 minutes is the average sleep cycle length, some studies show that our sleep cycles differ, indicating values between 80-120 minutes, depending on our circadian rhythm.
What are the sleep cycle stages?
If you want to learn more about what happens while we sleep, you're on the right path. In this section, we'll go through the four stages that make up a sleep cycle.
As we mentioned, the sleep cycle is divided into four stages. Each of them is characterized by different brainwave frequencies and eye and muscle movements. This allows us to group the stages into two categories:
- Three Non-REM (NREM), stages 1, 2 and 3; and
- One Rapid Eye Movement (REM), or stage 4.
Let's take a closer look at the peculiarities of each of these stages:
-
Stage 1, a.k.a. NREM1, is the lightest sleep phase. You may experience involuntary muscle contractions and other random movements during this stage. The eye movement slows down, and brain waves begin to slow down. This phase lasts between 1 to 7 minutes, and waking up is quite easy.
-
Stage 2, or NREM2, is a light sleep. In this phase, your body is more relaxed, and you may start to experience sensations such as floating and involuntary movements. The eye movement stops, and brain activity slows. This stage lasts 10 to 25 minutes and is more difficult to be awakened. If you're awakened during this stage, you may feel disoriented.
-
Stage 3, also known as NREM3, deep sleep or slow-wave sleep. This is the stage in which the body and mind recover, body tissue is repaired, your body builds bone and muscle, your heart rate is at its slowest, and your brain waves slow even more. This stage can last 20 to 40 minutes and is difficult to wake up from, but if you do, you'll feel dizzy and disoriented.
-
Stage 4, or REM, is the final and the most active phase, with the brain wide awake. During this stage eyes move rapidly, your heart rate increases, you experience vivid dreams, and your arms and legs become paralyzed. The duration of this stage gets longer as we complete each sleep cycle. The first REM can last around 10 minutes, while the last can endure for up to an hour. Being awakened during this stage can impact your mood.
Using the sleep cycle calculator
In this section, we’ll show you how to calculate the best time to sleep and wake up using the sleep cycle calculator:
-
First, in the Time to fall asleep field, write down how long it takes you to fall asleep. The calculator shows 15 minutes as default.
-
After that, select the time you need to wake up from the Waking up time drop-down menu.
-
Finally, the calculator results will show you when you should go to bed based on your input information.
Take note that these wake-up timings are calculated to span whole sleep cycles.
For instance, let’s imagine it takes you 8 minutes to fall asleep, and you need to wake up at 7:00 am. According to this information, to complete 5 sleep cycles (7 h 30 min), you must go to bed by 11:22 pm.
🙋 Tick on the Enter custom sleep cycle lengths checkbox to change the sleep cycle lengths values.
As an additional feature of this tool, you can also determine when you should wake up so you have slept complete sleep cycles. All you have to do is click on our tool's Your wake-up times heading and select your desired sleeping time. Our sleep cycle calculator will then display the list of your recommended wake-up times.
More sleep calculators!
So you're a sleep enthusiast who's obsessed with everything sleep-related? Then you might want to check at some of our other sleep-related tools:
How long is a sleep cycle?
On average, a sleep cycle lasts 90 minutes and varies as we grow. For example, a child’s sleep cycle takes between 40-50 minutes; by the time they’re five years old, the sleep cycle has matured and lengthened to 90 minutes.
How many sleep cycles do I need per night?
It depends. Our genetics determines the number of sleep cycles we need per night. On average, people need 5 cycles (7 h 30 m) of sleep per night. However, some people only need 4 cycles (6h), while others need 6 cycles (9h) of sleep per night.
What time should I go to bed to complete 6 sleep cycles?
To wake up at 6:30 am, you'd need to go to bed at 9:15 pm to complete 6 sleep cycles. To obtain this result:
-
Convert the number of sleep cycles into hours. Considering 90-minute cycles:
6 sleep cycles = 9 hours
-
Consider how long it takes to fall asleep and add it to the previous result. On average, it takes 15 minutes. This totals 9 h 15 min.
-
Work back 9 h 15 min from your desired wake-up time. For our example, this is 9:15 pm.