Getting enough sleep helps keep your mind. REM sleep should make up around 20% to 25% Trusted Source MSD Manuals First published in 1899 as a small reference book for physicians. 5 hours of sleep. One thing we really like about this formula is how reasonable/attainable it is. Ernest Hartmann, MD described the 90-minute sleep cycle as a basic or general 90-minute cycle of our night’s sleep and is determined by electroencephalogram and REM criteria. Make sure to set an alarm. This could look like five hours of sleep and a one hour nap or six hours of sleep and a 20-minute nap. 2022. Help. Once you reach "second wind," which is when you feel a burst of energy around this time, you start taking 20 minute naps every 2 hours and 40 minutes. Sleep apps like Sleepyti. But, that is a guide. The National Sleep Foundation recommend taking a 20-minute nap to wake up feeling refreshed. In the first few weeks of life, a sleep cycle consists of both active and quiet sleep periods in equal proportion. 5 hours; 60-year-olds take 18 minutes to fall asleep and sleep for 6. The REM Nap: 90 to 120-Minute Nap. There are two basic types of sleep: rapid eye movement (REM) sleep and non-REM sleep (which has three different stages). Do babies have 45 minute sleep cycles? Yes. 05. Due to the nature of the human sleep cycle, naps longer than 30 minutes might induce a phenomenon called sleep inertia, in which you feel confused and groggy for a brief period upon waking and your. If it is not possible to sleep for a full 90 minutes, the next-best option may be to cut the sleep short and have a 15-20 minute power nap instead. This isn't a new concept, of course. The premise is that our bodies go through alternating periods of rest and activity, and that each full rest-activity cycle lasts between 80–120 minutes. The 20-minute nap. You spend about 25% of your night in this stage of sleep. “That means your REM cycle might be. This will leave you feeling more refreshed and less stressed. You will be more refreshed and closest to your waking state at the end of a cycle. Most people have a regular sleep cycle of about 90 minutes. Don’t use electronics. If you are not sleep deprived, then shorter naps of less than 30 minutes are best. Deep sleep: The third stage in the sleep cycle, deep sleep, or slow wave sleep is the most restorative sleep phase. During deep sleep your body strengthens muscle, bones, tissue, and immune function. The cycle starts over every 80 to 100 minutes. After stage 4 you usually enter an episode of REM sleep. Each snooze duration becomes shorter, gently bringing you from asleep to completely awake at your desired alarm time. muscle tension. REM sleep begins around 90 minutes into the night, lasting only 10 minutes for the first episode and increasing with every additional cycle, with the highest period of the night averaging an hour. If you work a daytime schedule, a brief (<20-minute) nap is recommended. [1] Here are some basic tips for healthful napping: Sleep for no longer than 30 minutes: The ideal nap duration is around 20 minutes and should be no longer than 30 minutes. The Uberman is a polyphasic cycle that consists of 6 to 8 equidistant naps across the day, each lasting 20 minutes. “This adds up to roughly about 7 to 9 hours of sleep to accommodate the range. Sleep is lighter at the end of a sleep cycle, which means a 90-minute nap should only cause a brief period of. While the prevalence of polyphasic sleep is unknown, anecdotal reports suggest attempts to follow this practice are common, particularly among young adults. During this stage, delta brain activity increases and you may. This is hard, but necessary. allowing 15 minutes to fall asleep. During sleep, your body cycles through four different. Dreaming is part of this sleep cycle. Between 20 and 30 minutes is a napping sweet spot, according to Dr. Everyman Sleep Schedule: This schedule includes sleeping for three hours during the night and supplementing with three 20-minute naps throughout the day, for a total of four hours of. 6 to 12 years: 9 to 12 hours. First/Second Sleep Schedule: The original biphasic sleep schedule, from the preindustrial era, split sleep into two segments during the. This occurs between the end of one sleep cycle and the beginning of a new one. I’m at my wits end I feel like his on me all day. 11 p. Most people will need between 5-6 sleep cycles per night. completing five or six 90-minute sleep cycles. A healthy sleep latency period typically ranges from 15 to 20 minutes Trusted Source UpToDate More than 2 million healthcare providers around the world choose UpToDate to help make appropriate care decisions and drive better health outcomes. The sleep cycle does not proceed directly from NREM to REM sleep, it progresses through the stages of NREM sleep from light to deepDr. FAQs. Sleep cycles are 90-minute sequences which move through the four different sleep stages and each sleep stage lasts between 5-15 minutes. After that, baby transitions into deeper, or non-REM, sleep. These 90-minute sleep cycles result in more or fewer sleep cycles per night, depending on how long you sleep. REM sleep may only last one to five minutes in the first cycle, and it gets longer and longer with each cycle. 2. • Vivid, full-color dreaming occurs; less vivid dreaming occurs in other stages. A newborn’s sleep cycle is unique. The efficacy and safety of this and other. Overall, it accounts for more than 50% of sleep in adults. Use the 90-minute sleep rule. Getting as much REM sleep as possible – around 10-20 minutes each cycle – is important for a healthy brain and helps with memory function and even creativity levels. If you have time and a need for a longer nap, napping for 60 to 90 minutes is enough time to have deep, slow-wave sleep, but end up in the lighter stages of sleep so you feel alert when you awake. Each cycle starts with light sleep, then you enter deep sleep, then dream then back to light. If you nap for more than that, you may feel more sleepy than ever. “What’s interesting is that some signatures of. The bear: Breus tells mbg there's a simple formula you can use to figure out the best bedtime for you. Research at NASA showed when pilots slept for 26 minutes, alertness improved by 54%, and job performance improved by 34% compared to pilots who didn’t nap. Anyway, the first three stages fall into the first category, whereas the last stage is reserved for REM sleep. ”. Mednick, who explains how during this “power nap,” you get enough stage two sleep to switch your body and mind into full relaxation mode. Sleep specialists argue that the best way to change your sleep cycle is. NREM3 makes up about 15% to 20% of your total sleep time. Any longer and you’ll fall into a deeper sleep cycle, which lasts for about 90 minutes. Aim to nap for only 10 to 20 minutes. You spend about 25% of your night in this stage of sleep. The language is quite complex to understand in general. Regular snooze. Only use your bedroom for sleep. Make it early. “One of the most misunderstood facts about baby sleep, in my experience, is that waking is not normal. Until around the 4-month mark (when sleep starts to get more “adult-like”) your baby really only has 2 sleep cycles: Newborn Sleep Cycle 1: Light (Active) Sleep. If you really want to nap for more than 20 minutes, you should instead nap for 90 minutes. It suggests sleeping time based on the stages of sleep, which will help to avoid waking up in the middle of a sleep cycle. Short naps are typically naps that last less than one sleep cycle (about 50 minutes). Stage 1 typically lasts up to 10 minutes. The longest periods of this stage occur during the first several sleep cycles. How to Use the Calculator. Others prefer to sleep for a shorter time period during the night (say, around five hours) and then take a longer nap of approximately 90 minutes in the. During this stage, you will have sleep spindles which are sudden rapid bursts of brain wave activity. Brain activity of diving seals reveals short sleep cycles at depth. Intelligent snooze lets you snooze through your wake up phase. The first half of the night is when we tend to get the most N3 sleep, with each 20-40 minutes session getting shorter as the night continues. Understanding the different stages of sleep and aligning your sleep. Make sure. She is rustling, she is stirring, maybe. Vivid dreams may occur during REM sleep. Telsa also followed the Uberman sleep cycle and claimed to never sleep for more than two hours a day. A complete cycle through the four stages of sleep can take from 70 to 120 minutes. Usually when you are sleeping, you begin at stage 1 and go through each stage until reaching REM sleep, and then you begin the cycle again. On average, it takes 15 minutes. Because this seems the most restrictive, it’s best for those who can follow a rigid polyphasic sleep schedule. What Time Should I Go To Sleep? There is no “one size fits all” bedtime, but there are ways to determine optimal bed and wake-up times based on age, geographic location, lifestyle. So try one of the apps or alarm clocks others have mentioned (or if you only have a crappy flippy phone like me and don't intend to get an. Plants, animals, fungi and cyanobacteria all operate on a circadian rhythm and are often modulated by external cues like sunlight and temperature. m. The key to successful power napping is its length. 30-90 minute naps may be beneficial for athletes who are sleep deprived and who need optimal muscle growth and repair. The idea behind “wake to sleep” is that you’re “supporting” your child through the transition from one sleep cycle to the next. So try one of the apps or alarm clocks others have mentioned (or if you only have a crappy flippy phone like me and don't intend to get an. The first 20 or so minutes of a nap are light sleep, or REM sleep. Sleep is lighter at the end of a sleep cycle, which means a 90-minute nap should only cause a brief period of sluggishness from. If you fall asleep too quickly or not quickly enough, it can have a major effect on your overall sleep-wake cycle and the quality of sleep. So instead, the typical 50-55 minute newborn sleep cycle includes only about 20 minutes of quiet sleep. 3. , wake up at 7:09 a. Go to another room and read or do other quiet activities until you feel sleepy. For da Vinci's possible adoption of this practice, Claudio Stampi writes in his 1992 book, "Why We Nap": "One of his. Characteristics of Stage 2 NREM sleep: • Lasts about 20 minutes. So, 10-20 minute naps should be just the ticket! It a actually does, given that you are properly trained. Narcolepsy is a chronic neurological disorder that affects the brain's ability to control sleep-wake cycles. Earlier exercise, avoiding daytime naps, and caffeine, large meals, and alcohol before bed, having a relaxing bedtime. By setting an alarm for 15 to 20 minutes, you reap the benefits of sleep spindles and wake up with renewed energy to complete your day’s work. 6% of nappers feel groggy after waking up. Devise a schedule that incorporates the 90 minute cycles,. , this isn't going to happen overnight. Usually, sleep cycles fall into 90-minute patterns. Humans sleep in cycles of about 90 minutes. Avoid daytime napping. A. Speaking from personal experience, I found that setting an alarm for 1 cycle is rarely reliable, but setting one for 3 cycles worked well for me; when I was in high school I used to randomly jerk awake somewhat regularly. M. If 15 to 20 minutes isn’t enough, aim for. Each stage can last from 5 to 15 minutes. A healthy sleep cycle consists of multiple stages. If you nap in the morning, the sleep consists primarily of light NREM (and possibly REM) sleep. It is sometimes called the ultradian sleep cycle, sleep–dream cycle, or REM-NREM cycle, to distinguish it from the circadian alternation between sleep and wakefulness. Da Vinci followed an extreme form of a polyphasic sleep schedule called the Uberman sleep cycle, which consists of 20-minute naps every four hours. Bedtimes are based on: your wake-up time. “There’s an idea that everyone sleeps in 90-minute cycles but that’s an average, not a rule,” says Winter. the first stage lasts for about 5-10 minutes, the second stage lasts for about 20 minutes, and the third stage lasts for about 30 minutes. Sleep Latency. Ultimately, NASA recommends a 10-20-minute nap to avoid falling into deep sleep. People with insomnia get less deep sleep and more likely to get Alzheimer’s disease. In order to attain optimal post-nap performance, a Stage 2 nap must be limited to the beginning of a sleep cycle, specifically sleep stages N1 and N2, typically 18–25 minutes. or what we call a 'worrying time' for 20 to 30 minutes before. Naps may get shorter as we age, to about 43 minutes in adults ages 55 and older. You either sleep for 15 to 20 minutes or a full sleep cycle of 90 minutes to make the most of your nap time. ” If your sleep lasts less than 20 minutes, you are still in the first stage of your sleep. – Stage 4/REM: REM sleep is thought to be essential for cognitive functions such as memory, learning and creativity. Sleeping between 90 and 110 minutes gives your body time to complete one full sleep cycle and can minimize grogginess when you wake. Typically, the body cycles between non-REM and REM sleep over a period of 90 minutes on average, and should occur 4-6 times in a good night's sleep. Catnapping is one of the most common complaints among new parents who visit this site. After about 20 minutes of slumber while in REM sleep, dreams usually begin for the average dog. For me at least, it is all too easy to enter into a deep stage of sleep at the end of the 30 minutes. Too little is… well it’s just not enough. Napping for longer than 20 minutes risks going to deep into the sleep cycle, which can result in feeling more tired and groggy, rather than rested. This means we should. This is followed by around 20 minutes of activity, known as REM sleep. 9 minutes. 1 hour before bed: cut off screens. The composition of a sleep cycle changes throughout the night too. You may wake up briefly between cycles. It is known as a “Power nap. A short nap like this allows your mind and body to rest without entering the deeper stages of sleep. 5 hours of sleep a night, while six full cycles are about 9 hours of sleep. Each sleep cycle takes between 70 and 120 minutes Trusted Source Division of Sleep Medicine at Harvard Medical School A production of WGBH Educational Foundation and the Harvard Medical School Division of Sleep Medicine. That said, naptime (or your “second sleep”) should be timed to last either 30 minutes or 90 minutes, but nothing in between, to avoid interrupting your sleep cycles. When we study the usual criteria of sleep like REM, amount of sleep, number of awakenings at night,. Stages three and four are deeper stages of sleep that you are not so easily awoken from. Each night, your body cycles through four stages of sleep, which repeat about four to six times in a row. A 15 to 20-minute nap can be a great way to help get rid of a sleep deficit. When a baby is born, he or she will sleep for 14 to 20 hours per day. Brain-wave patterns showed that seals took short (less than 20 minutes. “It takes 20 minutes after your eyes shut to get into restful, restorative sleep. can interfere with nighttime sleep. Typically, a person goes through 4-6 sleep cycles per night, which last approximately 90 minutes per cycle, but can range from 70-110 minutes long. The term power nap was coined by Cornell University social psychologist James Mass. Stage 3 An average sleep cycle lasts about 90 minutes. The mean polycyclic sleep-wake cycle was 83 min. While sleeping, our brains go through several sleep cycles. In the final cycle is may last up to an hour. Regular snooze lets you choose a specific snooze time between 1-20 minutes. Take naps in the early afternoon. 80. On average, adults go through 4–6 sleep cycles per night and spend 90 minutes in each sleep. In your first sleep cycle, you may only spend 10 minutes in REM, but later in the night this stage may last around 60 minutes. Each stage progresses sequentially through light sleep, deep s/leep, and REM cycles which repeat on 90-110 minute intervals. NREM-2. ” If your sleep lasts less than 20 minutes, you are still in the first stage of your sleep. Baby sleep cycles are around 50 minutes long. Polyphasic sleep is the practice of sleeping during multiple periods over the course of 24 hours, in contrast to monophasic sleep, which is one period of sleep within 24 hours. Coffee nap (aka caffeine nap) A cousin to the power nap, the coffee nap is a funny concept for some people to wrap their head around. The exact number of hours, or sleep cycles, you need at night will vary depending on a number of factors, including: Your age, as children and younger adults tend to need more sleep; Your gender, as women tend to need 20 more minutes on average than men;Deep sleep lasts 20 to 40 minutes 11. Your first sleep cycle will likely cover 70 to 100 minutes, while later sleep cycles should last 90 to 120 minutes. In most people, a power nap length of 15 to 20 minutes is just perfect. Most people go through four or five cycles per night (assuming they get a full eight hours of sleep). To Conclude. The duration of REM sleep increases from 10 minutes in the first cycle to up to 50 minutes in the final cycle; note that slow-wave (stage IV) sleep is attained only in the first two cycles. "This cycle repeats four to five times throughout the night. Each cycle contains four individual stages: three that form. The human body cycles through two phases of sleep, (1) rapid eye movement (REM) and (2) non-rapid eye movement (NREM) sleep, which is further divided into three stages, N1-N3. But young babies spend only a minority of their time in quiet sleep — approximately 20 minutes per sleep cycle (Grigg-Damberger 2017). A 10-20 minute nap is advisable unless you are behind on sleep. Give the “10-3-2-1 method a look: 10 hours before bed: cut off caffeine. For the point of our discussion, anything less than 50 minutes will be classified as a “short nap. This could look like five hours of sleep and a one hour nap or six hours of sleep and a 20-minute nap. It seems that if you wake up then, you’ll feel more rested. This clock controls a number of processes, including sleep-wake cycles. Sleep Phases and Stages. 10 to 20 minutes is the perfect nap length. The calculator will tell you when to go to sleep for recommended 4 to 6 sleep cycles. Because the goal of a good nap is to re-energize your mind and body, the best nap length ensures you are not entering REM or deep sleep stages, but only staying in light sleep. Sleep restriction therapy rather than sleep deprivation therapy for insomnia. 9:30 AM –. There was an average of two REM sleep episodes per sleep-wake cycle. However, the general consensus is that either a short power nap (10-20 minutes) or a full sleep cycle (about 90 minutes) is best. 20 minutes. Some people completely or partially wake up after the sleep cycle ends, while others stay asleep until morning. ”Each cycle is around 90 minutes. On average, it takes about 15 to 20 minutes to fall asleep. Circadian rhythms are physical, mental, and behavioral changes that follow a 24-hour cycle. Others prefer to sleep for a shorter time period during the night (say, around five hours) and then take a longer nap of approximately 90 minutes in the. An average adult spends around half of their sleep in this stage. The efficacy and safety of this and other. This amounted to about 5 hours of sleep every 24 hours. Sleep cycles take 75 to 90 minutes to complete. Each sleep cycle consists of four stages, with each having varying effects on the body. Turns out, 90 isn’t the magic number. 5 to 9 hours of sleep) for optimal rest and recovery. Biphasic (or diphasic, bifurcated, or bimodal) sleep refers to two periods, while polyphasic usually means more than two. Polyphasic-sleep. 30pm. The human body cycles through two phases of sleep, (1) rapid eye movement (REM) and (2) non-rapid eye movement (NREM) sleep, which is further divided into three stages, N1-N3. Each complete sleep cycle takes from 90 to 110 minutes. 6-10 months, babies go to 2 naps. adults have taken a nap in the past three months. The language is quite complex to understand in general. You cycle through all stages of non-REM and REM sleep several times during a typical night, with increasingly longer, deeper REM periods occurring toward morning. If you're going to sleep now, you can check when to wake up to feel well-rested without inputting anything. When you dream, you are not fully conscious, so while your dreams can be quite vivid and seem very real, you do not actually smell, taste, or feel anything. For example, you may want to have a core nighttime sleep schedule from 1am until 4:30am, then a 90 minute to three hour nap from 12 noon until 1:30pm or 3pm. Sleep cycles usually repeat every 90 to 110 minutes. However, for most babies older than 2-4 months, normal naps fall within the ranges of normal baby sleep outlined here. Set an alarm for 15 to 30 minutes to wake up. This causes disruptions to their natural sleep-wake cycle, with ramifications that can lead to less restful sleep, less sleep overall, and more sleep-related accidents and illnesses,. “There’s an idea that everyone sleeps in 90-minute cycles but that’s an average, not a rule,” says Winter. You either sleep for 15 to 20 minutes or a full sleep cycle of 90 minutes to make the most of your nap time. You simply count back from when you want to wake up, and factor in the time you need to. This results in about 5 hours of sleep every 24 hours. 5 to 12 years: no nap needed if they’re getting the recommended 10 or 11 hours of sleep per night. M. REM Sleep Patterns. Dreams occur during this stage of sleep, from which we are equally challenging to awaken. Most experts recommend that healthy people who are not sleep-deprived take short naps, defined as ranging from five to 20 minutes. 2. That said, naptime (or your “second sleep”) should be timed to last either 30 minutes or 90 minutes, but nothing in between, to avoid interrupting your sleep cycles. Our eyes begin to flicker, and our brain activity increases as we reach the REM phase. Our understanding of sleep stages keeps evolving: Prior to 2007, many. During this stage, your muscles become more relaxed and you may begin to have slow-wave (delta) brain activity. Exercise 20 to 30 minutes a day but no later than a few hours before going to bed. The general advice is that you either take a short nap (20 minutes or so) so that you never make it to the deeper non-rem stages of sleep or take a 90 minute(ish) so that you complete one sleep cycle. REM sleep accounts for a little less than 25% of total sleep in adults. Avoiding liquids reduces your chances of needing to get up to use the bathroom in the middle of the night. While adult sleep cycles are usually around 90 minutes, babies have shorter sleep cycles. Power naps are unlikely to interfere with nighttime sleep if taken in the early or mid-afternoon. There are three phases of non-REM sleep. Most people have a regular sleep cycle of about 90 minutes. To make sure your power nap doesn’t turn into a marathon sleep sesh, set an alarm to wake you after 20 or 30 minutes. A long sleep latency means it takes longer than 20 or 30 minutes to get to sleep. We included that time when calculating your result. This cycle is much easier to adjust to than the Uberman and allows for more flexibity in nap times and in skipping naps when necessary. FAQs. The best length for a nap is 10-20 minutes. As the night progresses, periods of REM sleep get longer and alternate with stage N2 sleep. During this stage: eye movements become. Over a 24-hour period, this could result in more than six 20-minute naps, resulting in just 2 or 2 hours of sleep in total – far fewer than the recommended amount of healthy adults. Heads-up: How your sleep is structured is known as sleep architecture. Each stage has a different duration, and for some of the stages, their duration will change throughout the course of the night. Leonardo da Vinci's sleep schedule included 20-minute naps every four hours. Each stage can last from 5 to 15 minutes. 20 minutes of exercise, 20. Taking short 20-minute naps throughout the day may help give you recharge. For example, an individual may take six 20. 4 to 11 months: 12 to 16 hours. 3 hours before bed: cut off eating. The calculator will tell you when to go to sleep for recommended 4 to 6 sleep cycles. We need all the stages of a 90-minute sleep cycle but deep sleep - which only make up around 20 per cent of total sleep - is thought to be especially beneficial for physical and mental health. irregular brain waves,. Mednick, who explains how during this “power nap,” you get enough stage two sleep to switch your body and mind into full relaxation mode. At 20 months, we want to aim for 2-3 hours of daytime sleep. Understanding what it is that keeps you awake at night—say, the tendency to reach for your phone before bed or a penchant for midnight snacking—is key to repairing a broken sleep cycle. 16-20 hours: 50/50 split of sleep between night and day, waking every 2-4 hours to feed. A baby’s sleep cycle is primarily characterized by longer durations of rapid eye movement (REM) sleep, which researchers believe is crucial for meeting developmental milestones. During REM sleep, brain activity increases substantially. It’s excellent as you will get all the benefits of all the sleep stages without feeling groggy. 14 Each sleep period lasts only one or two sleep cycles. 11:15 p. Top 20 Proven Sleep Tips Sleep Hygiene SLEEP AIDS Melatonin Magnesium TOOLS & PRODUCTS. 20–40 minutes Stage 4 REM 10–60 minutes. (Four sleep cycles would give just six hours of sleep, six sleep cycles would give 9 hours of sleep per night) If you need to wake up by 7am then count back 7. One normal sleep cycle, including REM sleep, takes about 90 minutes. Researchers say a 20 minute nap is the best length. During this time your brain moves through five different stages. m. Each sleep cycle is made of four sleep stages and typically lasts 80 to 100 minutes. If getting that extra 30 minutes is not in the cards, then taking a 15 to 20-minute nap may. A toy poodle may dream every 10 minutes, while. Usually there are four to six cycles per night. Stage 2 non-REM sleep. 🧠. For example, if you want to wake up at 7 a. Everyman Sleep Schedule: This schedule includes sleeping for three hours during the night and supplementing with three 20-minute naps throughout the day, for a total of four hours of sleep each day. Sleep latency, or sleep onset latency, refers to the amount of time it takes to fall asleep. Stage 3 sleep generally accounts for 20 to 40 minutes during the first cycle and decreases later in the night. There are three phases of non-REM sleep. Biological Rythms. Uberman Sleep Schedule: Six 20-minute naps are spaced evenly throughout the day, totaling two hours of sleep per day. Different systems of the body follow circadian rhythms that are synchronized with a biological. In the first sleep cycles of the night, more time is spent in non-REM sleep. Spindles play an essential role in processing and consolidating memories. Use the 90-Minute Sleep Cycle Rule. And if it’s too bright, there’s no melatonin to help promote sleep. During your REM sleep cycle, your eyes are darting around and “seeing” different things. Try these expert tips to reboot good sleep and put sleep disruption to rest. If you sleep more or less, you risk interrupting these cycles and not resting well enough. Thus, it would be appropriate for you to wake up after one and a half hours. If your sleep-wake cycle changes as you get older, these tips may help: Go to bed and get up at the same time each day, even on the weekends. Midday Nap Sleep Schedule: With this biphasic sleep schedule, people swap the long siesta for a short, 20- or 30-minute nap during the day. Tell the cycle's calculator what time you want to. Have you ever heard of someone suggesting a 20 minute power nap? This is because it gives you some light rest before entering REM sleep. Each is linked to specific brain waves and neuronal activity. Here's a brief overview of each sleep cycle that occurs throughout the night: NREM Stage N1: This is when you fall asleep,. Instead, implement this hack in weekly 20 to 30-minute increments. This is the stage where your body is the most active during sleep. Considering 90-minute cycles: 6 sleep cycles = 9 hours. Continue indefinitely. Make sure. If you try to wake up during REM sleep, you wake up groggy and unhappy. The sleep calculator recommends when to go to sleep in order to wake up feeling refreshed. Stage 2: Stage 2 follows stage 1 and lasts about 10 to 25 minutes. In particular, napping for less than 20 minutes Trusted Source National Library of Medicine,. Generally, a person enters a REM sleep stage after they’ve been. It suggests sleeping time based on the stages of sleep, which will help to avoid waking up in the middle of a sleep cycle. m. In humans, this cycle takes 70 to 110 minutes (90 ± 20 minutes). One common variation consists of taking a 20-minute nap every 4 hours for a total of 3 hours of. Most people need 7–9 hours of sleep per night, but working out how much deep sleep.