Recently updated on: September 20, 2023
TL;DR - A sleep calculator helps determine your optimal sleep and wake-up times by setting the time of complete sleep cycles. It also helps you avoid waking up in the middle of a sleep cycle, which can cause sleep inertia and grogginess.
How much sleep do you get every night, on average?
If we're honest, eight hours of sleep is almost hard to come by these days, especially with all the distractions and time-consuming activities throughout the day. The hardships of modern life also contribute to our sleeping difficulties and sleep deprivation.
According to a Manulife Philippines survey, we are a sleep-deprived generation and a country with an average sleep of only six and a half hours, ranking us 4th in the world when it comes to sleep deprivation.
In connection to our sleeplessness, the Philippines is also among the world's leading users of mobile phones and social media. Coincidence? Maybe not.
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How many sleep hours do you need?
We need to sleep an average of eight hours, or at least seven hours every night, to maintain a healthy body and mind. Unfortunately, our current modern lifestyle hinders us from getting our needed rest.
It is widely known that blue light from electronic devices like smartphones can drastically affect our circadian rhythm, leading to trouble falling asleep and, in turn, less sleep.
As a result of our lack of enough sleep, our overall health can suffer in the long run. We can become physically weaker and our mental capacity faulty when we don't get enough sleep.
According to research, there are four sleep stages. They are analyzed based on the brain activity happening when we're asleep, which takes between 90 to 120 minutes per cycle.
There are three non-REM (rapid eye movement) sleep stages and one REM sleep stage.
- Stage 1 (NREM)/ N1/ Light Sleep - 1 to 5 minutes
- Stage 2 (NREM)/ N2 - 10 to 60 minutes
- Stage 3 (NREM)/ Deep Sleep/ Delta Sleep - 20 to 40 minutes
- Stage 4 (REM Sleep) - 10 to 60 minutes
How many sleep cycles do you need?
The goal is to get an average of four to six sleep cycles or around eight hours of sleep every night, but with so many things keeping us busy, such as work and studies, we sometimes take rest for granted.
Remember that sleeping early is a habit, so we must build it slowly.
Related: 10 Small Things That I Appreciated More After Entering Adulthood
What is a sleep calculator?
A sleep calculator (also known as sleep cycle calculator or sleep clock calculator) is a table or application which helps you determine the best sleeping or wake-up time so you can avoid waking up in the middle of a sleep cycle to have a better sleep quality.
A sleep calculator suggests the best time to wake up or to sleep based on 90-minute sleep cycles.
Though it can identify the end of a sleep cycle, allowing you to sleep for less than the ideal eight hours, it still suggests that you complete at least five or six sleep cycles each night.
Why should you use a sleep calculator?
I discovered the sleep calculator through one of Thomas Frank's YouTube videos. He mentioned that it is essential to complete sleep cycles to avoid the state of grogginess in the morning, also referred to as sleep inertia.
A typical person sleeps four to six sleep cycles, with each cycle taking about 90 mins long. The idea is that you should, as much as possible, wake up at the end of the sleep cycle. But how would you do that, you ask? Of course, by using a sleep calculator.
Several websites and mobile apps can compute your waking time or sleep time, but I use this one. It can even detect sleep cycles, sounds, and snoring.
How to use a sleep calculator?
First, you need to access a sleep calculator website like sleepcalculator.com or download a sleep calculator app like this one to calculate sleep cycle.

There are usually two options. The first is to set the time you want to wake up, and the other is to set the time you want to sleep.
If you set the time you want to wake up at 6:00 AM, the site or app will recommend an optimal bedtime time for you to sleep. It will also add 15 minutes that it usually takes for adults to fall asleep. It is also recommended to complete 5-6 sleep cycles for a good night's sleep.

The second way to use a sleep calculator is to compute the best time to wake up or set the alarm to maximize your sleep. For example, it is currently 12:58 AM. Considering complete sleep cycles, what would be the best time to wake up.

The site or app will suggest the best times to wake up, including the times to complete the 5-6 sleep cycles.
What are some good sleeping habits?
A good night's sleep is almost a difficulty for many, so to pay for the sleep debt, we must have good sleeping habits. Here are some:
- Consistent sleeping time. Sleep at the same time every day.
- Comfortable bed and pillows. Sleep using a bed where you're comfortable and soft pillows.
- Exercise regularly. Include exercise during the day. Just be careful not to exercise too close to bedtime.
- Avoid gadgets 30 mins before bed. Blue lights emitted by various electronic devices can mess up our circadian rhythm.
- Limit caffeine before bedtime. We love coffee, but it can affect our sleep if taken later in the day. You can try decaf coffees if you really can't stop.
Related: Gratitude Journaling
What if you're working on the night shift?
Personally, I will never prefer working on the night shift again because of its adverse effects on our bodies.
However, if you are working the night shift, a sleep calculator can also be useful as it will give you the correct sleeping and waking time.
Final Thought:
Sleeping is an essential part of our lives. It recharges us for the next day, clears our heads, and repairs our bodies.
Sleeping can remind us that we did a good job today. It can also tell us that though our day sucked, we still have a new day, new opportunities to be better, and new blessings that God has in store tomorrow.
Isn't it harder to sleep when we have too much anxiety and worry about a tomorrow that often never comes? Remember that we can always ask God for peace (Philippians 4:6-7).
We can't be intense every day to the point that we neglect sleep. Remember that sleeping is vital to anyone's success.
So, if you want to be successful and have a happy life, sleep. You may also use a sleep calculator if you need one.