We have affiliate relationships where we are paid a commission on sales through some of our links. See our disclosures.

Sleep Calculator

“Get 7-8 hours of sleep per night!” This recommendation is pounded into our heads day after day, night after night. While getting a certain number of hours of shut-eye is indeed important, normal sleep goes far beyond just clocking in and out. Instead, it’s characterized by length, quality, and timing, along with the absence of disturbances and disorders. (1)

Our sleep calculator helps get this timing just right. You simply enter what time you want to wake up in the morning, and it’ll tell you various times you can head to bed in order to complete a certain amount of sleep cycles and feel refreshed when you wake up.

You should try to fall asleep at one of the following times:

Please keep in mind that you should be falling asleep at these times. The average human takes fourteen minutes to fall asleep, so plan accordingly!

If you head to bed right now, you should try to wake up at one of the following times:

Please keep in mind that you should be falling asleep at these times. The average human takes fourteen minutes to fall asleep, so plan accordingly!

Sleepopolis Moon and Stars

I want to wake up at...


Sleep Calculator App: How it Works

Based on your specific snooze sitch, you might want to know the best time to sleep and wake up. The calculator does it all — showing you a variety of times to fall asleep and wake up in order to achieve a certain amount of sleep cycles.

Hold the Foam (Mattress): Sleep Cycle?

Let’s take a step back to explain what a sleep cycle actually is, along with what happens when our heads hit the hay at night. It turns out we don’t just fall asleep and wake up eight hours later, with no critical happenings charging through our system (how we wish it were that simple). Instead, our bodies go through a series of waves, called sleep cycles. There are five cycles in total, each lasting around 90 minutes.

The first four stages comprise our non-rapid eye movement (NREM) sleep, while the fifth stage is when we move into rapid eye movement (REM) sleep. Let’s look a little bit more closely at each one.

NREM sleep: This is more than just our eyes staying still. However, the name does hint at the importance of NREM. These four stages are building up intensity towards our REM sleep. Across them, the body moves from really light sleep (Stage 1) to a super deep sleep (Stage 4). By stage 4, it will be really hard to wake someone up. (2) Here’s a little bit more about each stage:

  • Stage 1 is considered the “transitional phase,” when we’re drifting in and out of consciousness
  • Stage 2 is the “light phase,” which is when our heart rate slows down and our core body temperature decreases
  • Stage 3 is “slow wave sleep.” Here, blood pressure drops, heart rate further slows, and our breathing becomes slower and more rhythmic
  • Stage 4 is “deep sleep,” a stage that doesn’t want to be disrupted. Your blood pressure, heart rate, and breathing are all very low.

REM sleep: At the end of our cycle, we actually enter a light stage of sleep. This is when, as the name suggests, our eyes dart up and down and all around, and is most likely when dreaming occurs. Blood pressure, heart rate, and breathing all begin to increase

  • Even though this stage is the most similar to being awake, it’s the furthest point from wakefulness in terms of the sleep cycle. It’s important to remember that we don’t go from being awake to being in REM sleep; rather, we must pass through all the stages of NREM first.

Which brings us to how we actually move through the sleep cycle! It’s important to note that each cycle isn’t, well, cyclical. Instead, we move from being awake, to stage one, two, three, four, and then three, two, one, before going into REM sleep! This cycle, which we like to think of as more of a “wave,” repeats over the course of the night. (3) Many scientists recommend going through 4-6 of these waves, which would provide six to nine hours of shut-eye (remember, each cycle is roughly 90-minutes long). (4) This is why the length of sleep is not what causes us to feel refreshed when we wake up. Rather, the key factor is the number of sleep cycles we complete. The difference between six hours and six hours 30 minutes can be huge; you don’t want to wake up in the middle of a cycle.

SO SleepCalculatorIcons Blue 181102

When to Wake Up: How Our Sleep Needs Change

As we journey through our own cycle of life, our bodies change, and we need different amounts of slumber. (5) Here’s a rough range of how much sleep we need depending on what stage of life we’re in, so you can use the sleep calculator based on age: (6)

  • Newborns: 14-17 hours
  • Infants: 12-15 hours
  • Toddlers: 11-14 hours
  • Pre-Schoolers: 10-13 hours
  • School-Aged Children: 9-11 hours
  • Teenagers: 8-10 hours
  • Young Adults: 7-9 hours
  • Adults: 7-9 hours
  • Older Adults (65+): 7-8 hours

Given these stats, our sleep calculator is best for adults who need up to nine hours of Zzz’s. We’re also working on a sleep calculator age for kids and teenagers since the algorithm is a bit different due to their varying sleep needs. Keep your eyes peeled for that!

Why Is Calculating Our Sleep Important?

It might seem counterintuitive, but it’s very possible to sleep for less time and feel more awake. That’s because it’s better to move through four full cycles (six hours of sleep) versus getting eight hours but waking up in the middle of REM sleep.

So while duration is indeed important — a 90-minute siesta per night probably won’t cut it — the number of complete sleep cycles we go through could trump the number of hours we’re getting.

All in all, calculating our sleep cycles might just be the missing link to our overall health. Optimizing our Zzz’s and better understanding when to hit the hay and when to wake up could add tremendous value to our lives, providing us with more energy, reducing the risk of chronic illnesses like cardiovascular disease and diabetes, combatting weight gain, and even improving our longevity. (7)(8) And who wouldn’t want to calculate their own sleep in order to live a longer and more energized life?

If you find yourself asking “does sleep calculator work for me?” there’s only one way to find out, and luckily there’s a lot of science to back up the role timing can play in our overall sleep health. Give it a whirl, and let us know how it works for you! And while the sleep calculator app will also answer “how long did I sleep?” remember that this data might not matter as much as figuring out if you fulfilled all of your sleep cycles!


    1. Medic G et al. Short- and long-term health consequences of sleep disruption. Nat Sci Sleep. 2017 May; 9: 151–161.
    2. Purves D et al. Stages of Sleep Neuroscience. 2nd edition. 2001
    3. Merica H et al. Internal structure of sleep cycles in a healthy population. Sleep. 1986 Dec;9(4):502-13.
    4. Cologne, G et al. What is “normal” sleep? Informed Health Online. 2016 Dec
    5. Ferrara M et al. How much sleep do we need? Sleep Med Rev. 2001 Apr;5(2):155-179.
    6. How much sleep do we really need? Sleep.org, https://www.sleepfoundation.org/how-sleep-works/how-much-sleep-do-we-really-need.
    7. Torbjörn Åkerstedt et al. Sleep duration, mortality and the influence of age. Eur J Epidemiol. 2017; 32(10): 881–891.
    8. Alvarez GG. The impact of daily sleep duration on health: a review of the literature. Prog Cardiovasc Nurs. 2004 Spring;19(2):56-9
The Sleepopolis team is all about helping you sleep better. Whether it is through extensive sleep product reviews, sleep tips, or debunking sleep myths, we're here for you!