While you sleep, you go through cycles of sleep states. The first state in a sleep cycle is light sleep, followed by deep sleep and a dream state referred to as REM-sleep. A full sleep cycle lasts about 90 minutes and is normally repeated several times each night. Your movements vary with each sleep phase. Sleep Cycle uses sound analysis to identify sleep states by tracking movements in bed. Sleep Cycle uses a wake up phase (30 minutes by default) that ends at your desired alarm time. During this phase Sleep Cycle will monitor signals from your body to wake you softly, when you are in the lightest possible sleep state.
There are three phases of non-REM sleep. Each stage can last from 5 to 15 minutes. You go through all three phases before reaching REM sleep.
Stage 1: Your eyes are closed, but it’s easy to wake you up. This phase may last for 5 to 10 minutes.
Stage 2: You are in light sleep. Your heart rate slows and your body temperature drops. Your body is getting ready for deep sleep.
Stages 3: This is the deep sleep stage. It’s harder to rouse you during this stage, and if someone woke you up, you would feel disoriented for a few minutes.
During the deep stages of NREM sleep, the body repairs and regrows tissues, builds bone and muscle, and strengthens the immune system.
As you get older, you sleep more lightly and get less deep sleep. Aging is also linked to shorter time spans of sleep, although studies show you still need as much sleep as when you were younger.
During the following stages our sleep gets deeper and deeper. After the fourth stage REM (Rapid Eye Movement) sleep begins. During this phase our heart rate and breathing gets faster. Blood pressure goes up and the brain starts to work but the body does not. That is why we don’t act out our dreams because the body is inactive. Most dreaming occurs in this phase. There can be up to seven such REM phases in one night.
Sleep studies have shown that we go through several cycles of light to very deep sleep each night. One phase of each cycle is called Rapid Eye Movement (REM) sleep. Whenever a researcher woke up a sleeper in REM sleep and asked what was happening, the sleeper always said, “I was dreaming.” In fact, even animals experience REM sleep, so we surmise that they, too, dream—but we cannot communicate with them to find out anything about the nature of their dreams.
REM stands for rapid eye movement. During REM sleep, your eyes move quickly in different directions. That doesn’t happen during non-REM sleep.
First comes non-REM sleep, followed by a shorter period of REM sleep, and then the cycle starts over again. Dreams typically happen during REM sleep.
Usually, REM sleep happens 90 minutes after you fall asleep. The first period of REM typically lasts 10 minutes. Each of your later REM stages gets longer, and the final one may last up to an hour. Your heart rate and breathing quickens.You can have intense dreams during REM sleep, since your brain is more active.
Babies can spend up to 50% of their sleep in the REM stage, compared to only about 20% for adults.
It’s easy to forget your dreams. In order to interpret your dreams you have to remember them, so forgetting them is a real problem. In fact, those who chronically forget their dreams tend to claim that they don’t dream. You will remember your dreams only if you wake up during, or just at the end of, a dream, but if you don’t wake up, or if you wake up just enough to turn over and fall asleep again, you’re not likely to remember a thing in the morning. To ensure that you remember a dream you can write it down as soon as you wake up from it; keep a note pad and a pen by your bed—and tell yourself, before you fall asleep, that you want to remember your dreams that night.
We have several dreams each night. Because we go through several cycles of REM sleep each night, we have many dreams each night, and at times you may be able to remember several of them each night. Sometimes, in the morning, as you review your notes of a dream from the previous night, you might remember other dreams that happened before or after the dream you transcribed.
One sleep cycle comprises of four stages and lasts for about 90-120 minutes. Note that some books list five stages in the sleep cycle. These books consider the first five to ten minutes when you are falling asleep as a stage in the sleep cycle. We think this is more of a transitional phase and not really part of the cycle, especially since this stage of sleep does not repeat itself, while the other four stages do repeat themselves throughout the night. For this reason, we have excluded as part of the cycle.
Dreams can occur in any of the four stages of sleep, but the most vivid and memorable dreams occur in the last stage of sleep (also commonly referred to as REM sleep). The sleep cycle repeats itself about an average of four to five times per night, but may repeat as many as seven times. Thus, you can see how a person has several different dreams in one night. However, most people only remember dreams that occur closer toward the morning when they are about to wake up. But just because you can’t remember those dreams do not mean that they never happened. Some people believe that they simply do not dream, when in reality, they just don’t remember their dreams.
The Stages of Sleep
The stages in the sleep cycle are organized by the changes in specific brain activity.
Stage 1: You are entering into light sleep. This stage is characterized by Non-rapid eye movements (NREM), muscle relaxation, lowered body temperature and slowed heart rate. The body is preparing to enter into deep sleep.
Stage 2: Also characterized by NREM, this stage is characterized by a further drop in body temperature and relaxation of the muscles. The body’s immune system goes to work on repairing the day’s damage. The endocrine glands secrete growth hormones, while blood is sent to the muscles to be reconditioned. In this stage, you are completely asleep.
Stage 3: Still in the NREM stage, this is an even deeper sleep. Your metabolic levels are extremely slow.
Stage 4: In this stage of sleep, your eyes move back and forth erratically as if watching something from underneath your eyelids. Referred to as REM sleep or delta sleep, this stage occurs at about 90-100 minutes after the onset of sleep. Your blood pressure rises, heart rate speeds up, respiration becomes erratic and brain activity increases. Your involuntary muscles also become paralyzed or immobilized. This stage is the most restorative part of sleep. Your mind is being revitalized and emotions are being fine-tuned. The majority of your dreaming occurs in this stage. If you are awakened during this stage of sleep, you are more likely to remember your dreams. These stages repeat themselves throughout the night as you sleep. As the cycle repeats, you will spend less time in stages 1 to 3 and more time dreaming in stage 4. In other words, it will be quicker and quicker for you to get to stage 4 each time the cycle repeats.When you’re scrambling to meet the demands of a busy schedule, cutting back on sleep may seem like the only answer. Sacrificing an hour or two of rest in order to get more done may sound like a reasonable trade-off. But the truth is that even minimal sleep loss takes a toll on your mood, energy, mental sharpness, and ability to handle stress. And over the long-term, chronic sleep loss wreaks havoc on your health.
By understanding your nightly sleep needs and what you can do to bounce back from chronic sleep loss, you can finally get on a healthy sleep schedule.
The quality of your sleep directly affects the quality of your waking life, including your productivity, emotional balance, creativity, physical vitality, and even your weight. No other activity delivers so many benefits with so little effort.
Sleep isn’t merely a time when your body shuts off. While you rest, your brain stays busy, overseeing a wide variety of biological maintenance that keeps your body running in top condition, preparing you for the day ahead. Without enough hours of restorative sleep, you won’t be able to work, learn, create, and communicate at a level even close to your true potential. Regularly skimp on “service” and you’re headed for a major mental and physical breakdown.
The good news is that you don’t have to choose between health and productivity. As you start getting the sleep you need, your energy and efficiency will go up. In fact, you’re likely to find that you actually get more done during the day than when you were skimping on shuteye.
Myths about sleeping:
– Getting just one hour less sleep per night won’t affect your daytime functioning. You may not be noticeably sleepy during the day, but losing even one hour of sleep can affect your ability to think properly and respond quickly. It also compromises your cardiovascular health, energy balance, and ability to fight infections.
– Your body adjusts quickly to different sleep schedules. Most people can reset their biological clock, but only by appropriately timed cues—and even then, by one or two hours per day at best. Consequently, it can take more than a week to adjust after traveling across several time zones or switching to the night shift.
– Extra sleep at night can cure you of problems with excessive daytime fatigue. The quantity of sleep you get is important, sure, but it’s the quality of your sleep that you really have to pay attention to. Some people sleep eight or nine hours a night but don’t feel well rested when they wake up because the quality of their sleep is poor.
– You can make up for lost sleep during the week by sleeping more on the weekends. Although this sleeping pattern will help relieve part of a sleep debt, it will not completely make up for the lack of sleep. Furthermore, sleeping later on the weekends can affect your sleep-wake cycle so that it is much harder to go to sleep at the right time on Sunday nights and get up early on Monday mornings.
How many hours of sleep do you need:
According to the National Institutes of Health, the average adult sleeps less than seven hours per night. In today’s fast-paced society, six or seven hours of sleep may sound pretty good. In reality, though, it’s a recipe for chronic sleep deprivation.
|Average Sleep Needs by Age|
|Newborn to 2 months old||12 – 18 hrs|
|3 months to 1 year old||14 – 15 hrs|
|1 to 3 years old||12 – 14 hrs|
|3 to 5 years old||11 – 13 hrs|
|5 to 12 years old||10 – 11 hrs|
|12 to 18 years old||8.5 – 10 hrs|
|Adults (18+)||7.5 – 9 hrs|
There is a big difference between the amount of sleep you can get by on and the amount you need to function optimally. Just because you’re able to operate on seven hours of sleep doesn’t mean you wouldn’t feel a lot better and get more done if you spent an extra hour or two in bed.
While sleep requirements vary slightly from person to person, most healthy adults need between 7.5 to 9 hours of sleep per night to function at their best. Children and teens need even. And despite the notion that our sleep needs decrease with age, older people still need at least 7.5 to 8 hours of sleep. Since older adults often have trouble sleeping this long at night, daytime naps can help fill in the gap.
The best way to figure out if you’re meeting your sleep needs is to evaluate how you feel as you go about your day. If you’re logging enough hours, you’ll feel energetic and alert all day long, from the moment you wake up until your regular bedtime.
If you’re getting less than eight hours of sleep each night, chances are you’re sleep deprived. What’s more, you probably have no idea just how much lack of sleep is affecting you.
How is it possible to be sleep deprived without knowing it? Most of the signs of sleep deprivation are much more subtle than falling face first into your dinner plate. Furthermore, if you’ve made a habit of skimping on sleep, you may not even remember what it feels like to be wide-awake, fully alert, and firing on all cylinders. Maybe it feels normal to get sleepy when you’re in a boring meeting, struggling through the afternoon slump, or dozing off after dinner, but the truth is that it’s only “normal” if you’re sleep deprived.
It’s not just the number of hours in bed that’s important—it’s the quality of those hours of sleep. If you’re giving yourself plenty of time for sleep, but you’re still having trouble waking up in the morning or staying alert all day, you may not be getting quality sleep.
The most damaging effects of sleep deprivation are from inadequate deep sleep. Deep sleep is a time when the body repairs itself and builds up energy for the day ahead. It plays a major role in maintaining your health, stimulating growth and development, repairing muscles and tissues, and boosting your immune system. In order to wake up energized and refreshed, getting quality deep sleep is essential.