Created by Jacek Staszak, Hanna Pamuła, PhD candidate and Kacper Pawlik, MD Show
Reviewed by Bogna Szyk and Jack Bowater Based on research by Hirshkowitz M, Whiton K, Albert SM, Alessi C, Bruni O, DonCarlos L, Hazen N, Herman J, Katz ES, Kheirandish-Gozal L, Neubauer DN, O'Donnell AE, Ohayon M, Peever J, Rawding R, Sachdeva RC, Setters B, Vitiello MV, Ware JC, Adams Hillard PJ. “National Sleep Foundation's sleep time duration recommendations: methodology and results summary.“ Sleep Health (March 2015)See 1 more source “Nighttime sleep duration, 24-hour sleep duration and risk of all-cause mortality among adults: a meta-analysis of prospective cohort studies“ Scientific Reports (February 2016) Last updated: Aug 30, 2022 This sleep calculator will help you find the best bedtime for you, by maximizing your full sleep cycles. Sleep consists of 90-minutes-long sequences, repeated throughout the night. You'll wake up feeling better if you wake up at the end of a cycle, rather than in the middle of it, so use this calculator to find out what time you should go to sleep if you want to wake up refreshed and alert. And if you are still wondering how important it is to get the right amount of sleep, check how deadly your current sleeping routine is! If you're interested in how much sleep we need at different ages, whether 6 hours of sleep is enough, what our natural sleep pattern is and what are 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 4 stages: the first three stages are non-REM stages, where stage 1 and 2 are known as light sleep stages, stage 3 is the deep sleep stage, and the last one is REM (rapid eye movement) sleep. The duration of each stage oscillates between 5 and 15 minutes. Early in the night, stages of deep sleep are longer than REM sleep, but this swaps round as the night progresses. 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 back to stages of light sleep and stages of deep sleep. Light sleep stages (N1, N2) are characterized by muscle contractions and being woke easily. Your body is preparing, slowly, for deep sleep, with your brain waves becoming slower. Deep sleep stage (N3, previously divided into N3 and N4) is also known as delta sleep or slow wave sleep. It's very hard to wake someone during this stage. It's also the most important sleep stage as it refreshes you the most and reduces your need for sleep. That's why if you nap for too long during the day (entering deep sleep) you don't feel as sleepy that night. Also, during this stage, your body and muscles are being restored by growth hormones. REM sleep stage (R) is where dreams happen. Your brain imitates waves just as if you were awake, with your eyes moving rapidly but still closed. How long is a sleep cycle?As we mentioned before, the average sleep cycle is 90 minutes. However, different sources give the values, varying between 90–110 minutes or even 80–120 minutes. Also, sleep cycles increase with age, starting from only 50-60 minutes during infancy. Animals have similar sleep patterns: a rat's cycle is as short as 12 minutes, a cat's - 30 minutes and an elephant's cycle is ~120 minutes. On average, it's proportional to the size and the metabolism rate of the animal - the smaller it is, the shorter sleep cycles it has. Why is a good night's sleep so important?While sleeping, our bodies are regenerating, which is why the quality of your sleep is very important. Waking up at the end of a sleep cycle makes you feel refreshed and happier - your body is 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, a healthier life routine, and a great mood! Sleep deprivationWho isn't guilty of going to sleep too late because of ‘binge-scrolling’ FB or Twitter? It's not just a social media addiction that means we sleep late, we often eat late, drink alcohol, or just stare at the TV without realizing it all leads to sleep deprivation that can cause, amongst other things, insomnia, premature skin aging, decreased sex drive and concentration problems. We also need to remember that sleep deprivation may be caused by more serious problems, such as obstructive sleep apnea (OSA); we can screen for this with tools like Epworth sleepiness scale, AHI or STOP-BANG. It is said that stress and irregular sleeping patterns can also lead to more nightmares, as well as weight gain. Not to mention being grumpy, miserable, and easily irritable – things that can seriously affect your relationships with other people. It has recently been proven that sleep deprivation also puts you at a higher risk of premature mortality! For more information see the sleep deprivation and premature mortality risk paragraph. How to improve your sleeping habits?A person who sleeps for only 4 full cycles (90 minutes each) feels better after waking up than someone who slept for 7 hours because they woke up at the end of their last cycle.
Another obvious thing affecting your sleep is your bed itself. A comfy mattress and a supportive pillow are also important for good sleep hygiene. How much sleep do I need?It all depends on the person and their age, as some of us feel great after only 6 hrs of sleep every night. However, according to the National Sleep Foundation, most of us need more than that:
Is 6 hours of sleep enough?Well – as usual – it depends. The values above are the recommended durations by National Sleep Foundation, but they are averaged over the entire population – everybody is different, and other sleep times may be appropriate. Some people only need to sleep for 4 or 5 hours – Margaret Thatcher was one of these short-sleepers, as she claimed to sleep only four hours a night. On the other hand, some people (long-sleepers) 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 genetic, like your height or eye color. In 2009, scientists found the gene (DEC2) associated with the "effectiveness" of sleep. Other researchers in 2014 compared how twins performed on some cognitive tasks – one sibling had the mutation in that gene, but the other did not. The study confirmed that the person with the short-sleeper mutation, which can come in a number 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 people's need for sleep is programmed from birth. Long-sleepers need to sleep a couple of hours more, while short-sleepers 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 the problems that insomniacs face – fatigue throughout the day, a need to nap, problems with falling asleep, staying asleep, or waking up frequently throughout the night. No, they just need less time to "clean up" their brains. Additionally, they also tend to be more optimistic and active during the day. Thanks to their syndrome, they can gain anywhere from 30 to even 60 extra days per year! How lucky, especially when compared to those poor long-sleepers. And you, what would you do with such an extra month of free time? Sleep deprivation and premature mortality riskScientists are more and more interested in the physiology of human sleep. In our modern society, people tend to live lives that never stop. We are experiencing a lot of stress: at work, in traffic, or even at home. When was the last time you felt your heart pounding in your chest or fear/anger burning deep in your soul? This results in an increase in problems sleeping, sleep deprivation, on a global scale. Doctors are beginning to see the effects of these lifestyle changes. Too little sleep has been already proven to be associated with an increased risk of stroke, coronary heart disease, hypertension, obesity, and type 2 diabetes. In the same way, sleeping for too long is also unhealthy. People who sleep for 8 hours or more have a higher risk of stroke, coronary heart disease, type 2 diabetes, and colorectal cancer. In a recent metanalysis, it has been shown that sleep deprivation increases the all-cause mortality risk. Metanalysis is a study in which scientists gather the results of many smaller studies to determine an association between two factors with more certainty. In this case, researchers analyzed 35 articles including over 2,400,000 participants in total. You can see the results with our sleep calculator. In the 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 of how to deal with these calculations:
Apart from using our sleep cycle calculator – which is a great tool, if a bit simplified (it assumes that your sleep cycle is equal to an average of 90 minutes) – you can try other ways to improve your sleep hygiene, such as this sleep cycle app. The program claims to monitor your sleep patterns and wakes you up in the lightest sleep phase. FAQHow to sleep for studying?We recommend you nap for a maximum of 30 minutes before you start studying because you will cover the first two stages of the sleep cycle. Napping for longer than this could make you feel even more tired as you'll likely fall into deeper sleep stages, and their are negative cognitive consequences for waking up during these. Now you no longer need to wonder "What time should I wake up?" How long is one sleep cycle?On average, one sleep cycle lasts 90 to 110 minutes. At the extremes, this can even reach 80 minutes per cycle or 120 minutes per cycle. It's important to mention that we are in the REM phase during the last part of the sleep cycle, which is when we start properly sleeping. How many sleep cycles per night do we have?On average, we should experience five sleep cycles, and if we take 90 minutes to be the length of a sleep cycle, we should sleep for 7 hours and 30 minutes. However, if you're an irregular sleeper, Omni's sleep calculator can recommends to you how much sleep time you actually require. How does a sleep cycle work?As explained in our sleep calculator, our body goes through 5 sleeping phases:
Jacek Staszak, Hanna Pamuła, PhD candidate and Kacper Pawlik, MD What time should I go to sleep? To wake up at the end of a sleep cycle, go to sleep at: 9:45 PM (6 cycles, 9h of sleep) - recommended for long-sleepers, 11:15 PM (5 cycles, 7h30m of sleep) - recommended for average-sleepers, 12:45 AM (4 cycles, 6h of sleep) - recommended for short-sleepers, 2:15 AM (3 cycles, 4h30m of sleep), 3:45 AM (2 cycles, 3h of sleep), 5:15 AM (1 cycle, 1h30m of sleep). If you go to sleep NOW, you should wake up at: 10:27 PM (6 cycles, 9h of sleep) - recommended for long-sleepers, 8:57 PM (5 cycles, 7h30m of sleep) - recommended for average-sleepers, 7:27 PM (4 cycles, 6h of sleep) - recommended for short-sleepers, 5:57 PM (3 cycles, 4h30m of sleep), 4:27 PM (2 cycles, 3h of sleep), 2:57 PM (1 cycle, 1h30m of sleep). How dangerous is my sleep routine? Night-time sleep duration Increase in mortality risk 0 % 20/20 Vision for 2020Acid-baseAlvarado score… 53 more What time is best to go to bed at?The 'Sweet Spot' for Bedtime: Between 10 p.m. and 11 p.m. Is Best for Heart Health. Researchers say falling asleep between 10 p.m. and 11 p.m. is the best time for heart health. They say that optimum bedtime fits well with circadian rhythms and daylight exposure.
When should you sleep calculator?Sleep calculator. Is sleeping from 10pm to 4am good?On the question of 10 pm-4am being the most ideal time to be asleep, Dr Nangia says, "According to the circadian rhythm, there are certain hormones which are at their peak during the night.
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