Falling asleep time
Waking up time
7:00 AM
What time should i go to sleep?
To feel like a young god, go to bed at 9:45 PM (6 cycles, 9h of sleep).
To get a decent sleep, lie down at 11:15 PM (5 cycles, 7h30m of sleep).
If you don’t have the time, go to bed at 12:45 AM (4 cycles, 6h of sleep).

Less recommended bedtimes:
2:15 AM gets you fresh morning but a lousy day (3 cycles, 4h30m of sleep).
Otherwise, try 3:45 AM (2 cycles, 3h of sleep).
Your last chance is at 5:15 AM (1 cycle, 1h30m of sleep).

What time should I wake up?
If you go to bed now, set your alarm clock to 5:36 AM (6 cycles), 4:06 AM (5 cycles), 2:36 AM (4 cycles), 1:06 AM (3 cycles), 11:36 PM (2 cycles) or 10:06 PM (1 cycle).

This sleep calculator will help you find out your bedtime on the basis of full sleep cycles. Our sleep consists of 90-minutes-long sequences, repeating throughout a night. You'll wake up feeling better if you wake up at the end of a cycle, rather than in the middle of it. Use the calculator to find out what time you should go to sleep if you want to wake up refreshed and alert.

If you're interested in how much sleep we need at different ages, whether 6 hours of sleep is enough or what are our sleep patterns and good sleep habits - keep scrolling and you'll find the answer.

What are sleep cycles and stages of sleep?

While sleeping, our brains go through several sleep cycles. An average person needs 5-6 cycles to feel fully regenerated in the morning. One sleep cycle lasts around 90 minutes and consists of 5 stages: first four stages are non-REM stages, where the stage 1 and 2 are known as light sleep stages, stage 3 (and 4 in the previous definition) as deep sleep stages, and the last one is REM sleep (rapid eye movement).

Duration of each stage oscillates between 5 and 15 minutes. Early in the night, stages of deep sleep are longer than REM, which reverses as the time passes. People's brains usually don't go from stages 1 to 5, but rather: stages of light sleep, stages of deep sleep, REM, and then again stages of light sleep and stages of deep sleep.

Light sleep stages (N1, N2) are the time when people can experience muscle contractions and wake up easily. Your body is preparing slowly for the deep sleep, with your brain waves becoming slower.

Deep sleep stages (N3, previously divided into N3 and N4) are also known as delta sleep or slow wave sleep. It's very hard to wake someone up at that time. It's also the most important sleep of all stages because it gives you the most refreshment and reduces your need for sleep. That's why, when you nap too long during the day, and you enter the deep sleep, you don't feel sleepy as the night progresses. Also, during that stage, your body and muscles are being restored by growth hormone.

REM sleep stage (R) is when dreams happen. Your brain imitates waves just as if you were awoke, with your eyes moving rapidly but still closed.

How long is a sleep cycle?

As we mentioned before, the standard, average sleep cycle is 90 minutes. However, different sources give the values between 90–110 minutes or even 80–120 minutes. Also, sleep cycles draw out with age, starting from only 50-60 minutes in infancy.

Animals have similar sleep patterns: rat's cycle is as short as 12 min, cat's - 30 minutes and elephant's cycle is equal to ~120 minutes. On average, it's proportional to the size and the metabolism rate of an animal - the smaller it is, the shorter sleep cycles it has.

Why is good night's sleep so important?

While sleeping, our bodies are regenerating. That's why the quality of sleep is very important. Waking up at the end of a sleep cycle makes you feel refreshed, happier and basically ready to face the day. The benefits of a good night’s sleep are also: better skin, no dark circles under eyes, smaller chances of eating disorders, healthier life routine, and a great mood!

Sleep deprivation

Who isn't guilty of going to sleep too late because of ‘binge-scrolling’ FB or Twitter? Apart from social media addiction, we often eat late, drink alcohol or just stare at the TV without realizing it all leads to sleep deprivation that can cause, e.g., insomnia, premature skin aging, decreased sex drive, and concentration problems. It is said that stress and irregular sleeping patterns can also lead to having more nightmares, as well as to weight gain. Not to mention being grumpy, miserable and easily irritable - this can seriously affect your relationships with other people.

How to improve your sleeping habits?

A person who sleeps only for full 4 cycles (90 minutes each) feels better after waking up than someone who slept for 7 hours because they woke up before the end of the last cycle.

  1. Set up alarms

    Yes, alarms. Setting up both for the time you should go to sleep and wake up can help in getting into a new, healthier routine. Plus, it's a friendly reminder for people who tend to 'get lost' on the Internet. Endless meme scrolling is fun, but it'll affect your day.

  2. Stop using the snooze button

    Although so popular 'just 5 minutes more' may feel great at first, in the long run, snoozing results in feeling tired in the morning, because these 5 or 10 minutes are not enough for your body to fall into the precious deep sleep. Believe us, it's worth getting up with your first alarm.

  3. No phone or computer policy

    It's also worth to stop playing with your phone or computer at least 2h before sleep time, as the blue light that their screens emit affects levels of melatonin (a sleep-inducing hormone) and as a result – falling asleep takes longer. Say goodbye to FB, TV, and tablets and enjoy a good night's sleep!

  4. No alcohol or coffee before sleep

    We all know that falling asleep after drinking is faster than while being sober, but is it healthy? Bad news here – it decreases the quality of your sleep, and in fact, you sleep less than you should to fully regenerate. Caffeine from coffee or theine from tea can also make falling asleep difficult - before the sleep time, choose the infusions with chamomile or valerian.

  5. Napping is great!

    Remember the time in kindergarten when you hated after-lunch napping? As soon as you start staying up late, you realize how much you miss these obligatory naps. If you ever feel exhausted during the day, try to include a healthy 15-20 min nap in your routine. It is proven to be way more refreshing than a full 90-min sleep cycle in the middle of the day.

  1. Regularity is key

One way of improving your sleep quality is keeping go-to-bed and wake-up times regular. Every day, you should try to respect your sleep patterns - indulgence once in a while shouldn't be a problem (like sleeping on one Sunday till noon), but don't make a habit out of it.

  1. Have a look at your bed and bedroom

TL;DR - think of your bedroom as a cave - it should be cool, dark and quiet. And comfy as well.

As you make your bed so you must lie on it. Take a critical look at a few essential aspects which can affect the quality of your sleep:

  • Temperature in the room.

    Your bedroom should be cool - typical ranges which you can find are equal to 60-67 °F (which is 15-19 range in °C - check it out with our temperature converter) or 65 - 72°F (18-22 °C). However, recommending specific values is difficult, as the temperature comfortable to one person may be not appropriate for another - so if it's too cold and you can't sleep, increase the temperature and adjust it to your needs. Just remember that it's easier to fall asleep in a cooler room, breath through your nose, and keep a set temperature of your brain and whole body. Also, too high temperature affects the REM sleep stage, essential for normal body physiology, so make sure that the heat doesn't affect your rest time.

  • As dark as possible.

    Darkness is essential to having a good quantity and quality of sleep. Light alters our internal sleep clock by inhibiting the rise of melatonin, known as sleep hormone. Make sure to remove all unnecessary sources of light - install curtains and shades on windows to block the outside light (the blackout curtains are the best ones) and consider using a sleep mask if you're traveling or sleeping in a place where it's difficult to block the light (like e.g. summer camping above the Arctic Circle). Preparation for bedtime is also an important issue - the intensity of light measured in lux shouldn't exceed 180 lux (normally-lit home is 300-500 lux), at least an hour before going to bed. That's the time for your body to quiet down, relax and prepare for sleep, so once again we remind you - don't stimulate your brain with any artificial lights from screens.

    You can read more about how light affects our sleep here.

  • Noise free area.

    That's the third significant feature of a sleep-friendly bedroom - good acoustic climate for sleep. According to WHO guidelines, the average night exposure should not exceed 40 decibels (dB), which is the approximate level of a quiet street. The study showed that room acoustics is important and it influences the sleeping patterns, shortening the deep sleep and REM sleep phase in bedrooms not acoustically insulated.
    How can you deal with noise disturbing your night rest? You can start from trying to modify your bedroom: by rearranging or adding some extra pieces of furniture to muffle the sound, investing in floor and ceiling insulation if noisy neighbors are the problem, sound-proofing your windows or covering the walls with absorbent acoustic panels. If these solutions are not possible or they don't give expected results, you can use active masking (white noise from fan or music) or use earplugs (snoring partner can be a nuisance).

Another obvious thing affecting your sleep is your bed itself. Comfy mattress and supportive pillow are also important for good sleep hygiene.

How much sleep do I need?

It all depends on a person and age, as some of us feel great after only 6h of sleep every night. However, according to the National Sleep Foundation, we need more than that:

  • Newborn to 3 months old: 14 - 17 hrs
  • 4 to 11 months old: 12 - 15 hrs
  • 1 to 2 years old: 11 - 14 hrs
  • 3 to 5 years old: 10 - 13 hrs
  • 6 to 13 years old: 9 - 11 hrs
  • 14 to 17 years old: 8 - 10 hrs
  • Young adults (18 to 25 years old): 7 - 9 hrs
  • Adults (26 to 64 years old): 7 - 9 hrs
  • Older adults (65+): 7 - 8 hrs

Is 6 hours of sleep enough?

Well - as usually - it depends. The values above are the recommended durations by National Sleep Foundation, but they are averaged for the population - everybody is different and other sleep times may also be appropriate. Some people need as short sleep as 4 or 5 hours - Margaret Thatcher was one of the short-sleepers, as she claimed to sleep only four hours a night. On the other hand, some people are drowsy if they don't sleep for 11 or 12 hours. Why is it so?

The response is simple - how much sleep you need is a genetically determined feature, as your height or eye color. In 2009, scientists found out the gene mutation associated with "effectiveness" of the sleep. Other researchers in 2014 compared the twins performance on some cognitive task - one sibling has the mutation in that gene, but the other not. The study confirmed that the person with the short-sleeper mutation, which can come in numbers of variants, performed better than the twin without the mutation. Still, it is believed that not one but multiple genes are involved.

To sum up, it looks like that some people are just short-sleepers from birth and they feel great and function normally after only a few hours of sleep. Short-sleeper syndrome isn't considered a sleep disorder, as such people don't have problems as insomniacs have - fatigue throughout the day, a need of a nap, problems with falling asleep, staying asleep, or waking up frequently throughout the night. No, they just need less time to "do the cleaning up" in their brains. Thanks to their syndrome, they can gain from 30 to even 60 extra days per year. Lucky beggars! And you, what would you do with such an extra month of free time?...

How to use the sleep calculator?

If you are wondering what time you should go to sleep, try out this sleep cycle calculator. Here is a step-by-step explanation on how to deal with these simple calculations:

  1. Think for a while about your habits: How long does it take for you to fall asleep? Let's pick 12 minutes for our example.

    Usually falling asleep time is equal to 10-20 minutes, so if you're not sure, leave our default value of 15 min. However, if you crash out the moment that your head hits the pillow or - on the other end of the scale - it takes you an hour or more, that may be the sign from your body. Everybody has ups and downs, exhausting days or a head full of problems, so if the problem with falling asleep doesn't happen often, it shouldn't be a big deal.

  2. Select the time you want to wake up. We've chosen to leave 15 minutes time intervals to simplify the calculator display. Assume we want to wake up at 7.15 a.m.

  3. The description below the sleep calculator tells you everything. We've included going to bed times with 6 to 1 full sleep cycles, but the first two - 6 and 5 full cycles - are definitely the ones to which we should aim.

    So, for our example:

  • The best idea would be to go to bed at 10:03 PM - then you'll sleep for full 6 cycles (9h).
  • Also a good option is to lie down at 11:33 PM - that fulfills the 5 cycles condition (7h 30m).
  • For some people, 6 hours sleep is enough - if that's you, go to bed at 1:03 AM, and you'll have 4 full cycles of sleep.
  • Other options are not recommended, as 4.5, 3 or 1.5 hours is not enough for us to rest and regenerate, even for elders who needs less sleep than kids or adults.
  1. If you're wondering what time should you wake up if you go to bed now, we have the answer as well - look at the last paragraph under the sleep calculator and you'll find the times of getting out of bed to wake up fresh and ready to work.

Apart from using our sleep cycle calculator - which is a great tool, but a bit simplified (it assumes that your sleep cycle is equal to average 90 minutes) - you can try e.g. this sleep cycle app. The program claims to monitor your sleep patterns and wakes you up in the lightest sleep phase.

Jacek Staszak and Hanna Pamuła, PhD student

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Sleep Cycle. Calculator | Definitions