Sleep Cycle Calculator + Online Solver With Free Steps

Sleep Cycle Calculator + Online Solver With Free Steps

Sleep Cycle Calculator + Online Solver With Free Steps

The online Sleep Cycle Calculator is a tool that helps to find the perfect time for going to bed for a person. The calculator takes the two values as input which are wake-up time and the number of sleep cycles.

The calculator returns the bedtime in hours and minutes, the time difference, and a clock image that also represents the time calculated.

sleep cycle calculator

What Is a Sleep Cycle Calculator?

A Sleep Cycle Calculator is an online calculator that can be used to calculate the exact bedtime depending upon the wake-up time and sleep cycles.

Human sleep can be further divided into certain short intervals of time. These intervals are called sleep cycles and are typically from 90 to 120 minutes. Every sleep cycle has some stages depending on the state of the body and its organs.

There is an average number of sleep cycles that every human goes through in one night. It is very essential to find the exact bedtime so that one gets an adequate amount of sleep. 

Sufficient sleep leads to a healthy life. The human brain gets refreshed and he can perform any task proactively. Therefore the Sleep Cycle Calculator aids you in quickly finding the right time to fall asleep.

This is a useful tool for doctors, patients, and every human being as it helps them to maintain a healthy sleep. This calculator works in your browser and is 24/7 accessible.

Moreover, this tool is free and has an unlimited usage capacity. Everyone can use it at all times and locations provided that they have good internet connections.

How To Use the Sleep Cycle Calculator?

You can use the Sleep Cycle Calculator by putting various wake-up times and sleep cycles in the provided fields. You just need to provide two inputs to get the results.

The interface of the calculator is easy to comprehend. The calculator has two spaces for both input elements with their respective labels and a click button for performing calculations.

There are some simple steps that you need to follow to correctly use this calculator. The step-by-procedure is given below.

Step 1

First, enter the wake-up time in form of hours and minutes (HH: MM). Also, specify the part of the day by writing the am or pm.

Step 2

Then insert the number of sleep cycles in the next field. The average number of sleep cycles is 4-6 and it is mentioned on the calculator too.

Step 3

Now click the ‘Submit’ button to gather the results.


The output of the calculator is divided into multiple steps. The first is input interpretation, which gives the wake-up time in form of hours and minutes and the sleep cycles in form of minutes by multiplying the number of cycles by 90.

It is a check feature where users can confirm the inputs to avoid any errors. Then it gives the bedtime, this is the time that one should fall asleep to fully get the specified sleep cycles.

It also gives the time difference between the current time and the recent bedtime calculated in the previous step. It displays the remaining time in hours, minutes, and seconds. 

Also, it gives the time required from bedtime to reach midnight which is 12:00 am. At last, it displays the clock picture with the bedtime. The needles of the clock are arranged in a specific manner to represent bedtime.

How Does the Sleep Cycle Calculator Work?

The Sleep Cycle Calculator works by determining the time the person should sleep according to the given wake-up time and the number of sleep cycles. This calculator helps the person to schedule his/her bedtime so that he\she can feel fresh in the morning.

The sleep calculator is accurate for an average person who wants to keep his/her sleep quality up to the mark. However, if the person is out of routine due to a workload that is affecting his/her quality of sleep then this calculator will not help him\her.

The time a human being needs to maintain quality of sleep depends on the number of sleep cycles and this calculator also calculates the sleep time based on sleep cycles.

What Is a Sleep Cycle?

A sleep cycle is the pattern of various activities a person’s brain goes through when he is sleeping. These patterns consist of muscle activity and eye movements. Sleep is not uniform therefore it is composed of several activities of the sleep cycle.

An average sleep cycle lasts about 90 minutes but all sleep cycles are not of the same duration it varies depending on the age. Sleep cycles start from 50 to 60 minutes each during infancy and this duration increases with increasing age.

An average person requires five to six cycles of sleep to feel fully fresh in the morning.

Stages of the Sleep Cycle

A sleep cycle consists of four stages, the first three stages are based on Non-Rapid Eye Movement (REM) sleep and the fourth one is based on REM sleep. The period of each stage is between 5 to 15 minutes.

The stages of deep sleep are much longer than REM sleep in the early night but as the night goes on this longer duration of deep sleep is exchanged with REM sleep. The four stages of the sleep cycle are explained below.

Light Sleep (N1)

The first stage is snoozing stage and the duration is of one to five minutes. The body is not fully breezy and calm during this stage however the body and brain waves become slower with twitches.

This stage is not suitable for a person because it is easy for someone to wake up that person nevertheless if a person is not disrupted they can quickly make progress to the second stage.

Light Sleep (N2)

The body moves to a more somber state in this stage. It includes a decrease in temperature, relaxed muscles, passive breathing, and heart rate. 

The N2 sleep leads to the slowness of brain activities as a whole and the brain waves show new patterns and eye movement is stopped. 

A person passes most of the sleep time in N2 sleep because it lasts for 10 to 25 minutes while in the first sleep cycle but its duration increases as the night progress.

Deep Sleep (N3)

This stage is also known as Delta sleep or slow wave sleep. It is extremely difficult to wake someone during this stage because the body relaxes much further and the muscle tone, pulse, and breathing rate also decrease even more.

The brain pursues identifiable patterns that are known as Delta waves. This stage is essential for the restoration of the body and muscles by growth hormones. It also boosts the immune system and other vital bodily processes.

Deep sleep also grants creativity, insightful thinking, and memory. N3 sleep has a span of 20 to 40 minutes during the early sleep cycles. However, as the sleeping continues, this stage gets smaller and most of the sleep time is consumed by REM sleep.

REM Sleep

REM sleep consumes 25 percent of the sleep cycle. The brain is most active in this sleep hence the dream occurs during this time and the eyes move back and forth under the eyelids although the eyes are closed.

This sleep is crucial for cognitive functions such as memory, learning, and creativity. The body undergoes atonia, which is a temporary muscle paralysis excluding the eyes and the muscles that control the breathing. 

A person does not fall into REM sleep until he is sleeping for 90 minutes. The duration of REM stages increases as the night progresses. The REM stage of the first sleep cycle spans only a few minutes but the later stages have a period of around an hour.

Solved Examples

To further understand the working principle of the calculator, let’s look at some problems solved using the Sleep Cycle Calculator.

Example 1

Alice wakes up early in the morning around 5 am and his average number of sleep cycles is 5. Find the perfect bedtime for him so that he can get the required sleep cycles.


The calculator provides the following solution to the given problem.

Input Interpretation

The inputs are given as follows:

05:00 am – 450 minutes


The best time to fall asleep for Alice is nine-thirty at the night.

09:30 pm

Time Difference

The difference between the current time and recent bedtime is:

2 hours, 30 minutes, 9 seconds ago

Time Until Midnight

The remaining time to reach midnight for bedtime is:

2 hours, 30 minutes

Example 2

If a person normally wakes up at 08:00 am and takes 6 sleep cycles to get sufficient sleep, then calculate the right time for the person to fall asleep.


The solution is provided in the following way.

Input Interpretation

The interpretation of the input is:

08:00 am – 540 minutes


The person requires 9 hours to complete the given sleep cycles. Therefore the bedtime is given as:

11:00 pm

Time Difference

The time difference is:

1 hour, 10 minutes, 1 second ago

Time Until Midnight

The time remaining at midnight is:

1 hour

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