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What Is A Sleep Cycle Called

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Sleep Drive And Your Body Clock

Have you ever noticed that you feel more alert at certain times of day, and feel more tired at other times? Those patterns are a result of two body systems: sleep/wake homeostasis and your circadian rhythm, or internal body clock. These systems determine your sleep drive, or your bodys need for sleep, at any given time.

What Happens When Your Circadian Rhythm Is Out Of Sync

The most obvious symptoms of your circadian rhythm being desynchronized are an inability to sleep when you should, or intense feelings of sleepiness when you are meant to be awake. Even if you do manage to fall asleep at night, you might not sleep as soundly and you could be easily awakened by external cues.

It’s also possible for different circadian rhythms within your body to fall out of sync with each other. This desynchronization among circadian rhythms can interfere with digestion, blood pressure, and other processes, and it likely contributes to the link between circadian rhythm problems and metabolic disorders .

Over the long run, disruptions to the circadian rhythm have been linked to a host of health problems, including obesity, diabetes, heart disease, and mood disorders .

Sleep Patterns Across The Night

Following the N3 stage of sleep, a series of body movements usually signals an “ascent” to lighter NREM sleep stages. Typically, a 5- to 10-minute period of N2 precedes the initial REM sleep episode. REM sleep comprises about 20 to 25 percent of total sleep in typical healthy adults. NREM sleep and REM sleep continue to alternate through the night in a cyclical fashion. Most slow-wave NREM sleep occurs in the first part of the night; REM sleep episodes, the first of which may last only one to five minutes, generally become longer through the night. During a typical night, N3 sleep occupies less time in the second cycle than the first and may disappear altogether from later cycles. The average length of the first NREM-REM sleep cycle is between 70 and 100 minutes; the average length of the second and later cycles is about 90 to 120 minutes. The reason for such a specific cycling pattern of NREM and REM sleep across the night is unknown. Some scientists speculate that specific sequences of NREM and REM sleep optimize both physical and mental recuperation as well as some aspects of memory consolidation that occur during sleep, but this has not been confirmed.

What Can Interrupt Your Cycle

Interrupted sleep is the term used to describe sleep that is not continuous throughout the night. When this happens, your sleep cycle can be disrupted. An in-progress sleep stage may be cut short and a cycle may repeat before finishing.

There are a number of issues that can interrupt your sleep cycles. Depending on which one is at play, this may happen occasionally or on a chronic basis.

Some factors that are associated with interrupted sleep and, therefore, may affect your sleep stages include:

  • Older age: Sleep naturally becomes lighter and you are more easily awoken.
  • Nocturia: Frequently waking up with the need to urinate
  • Sleep disorders, including obstructive sleep apnea and restless leg syndrome
  • Pain: Difficulty falling or staying asleep due to acute or chronic pain conditions, like fibromyalgia
  • Mood disorders such as depression and bipolar disorder
  • Other health conditions, including Alzheimer’s disease, Parkinson’s disease, obesity, heart disease, and asthma
  • Lifestyle habits: Little/no exercise, cigarette smoking, excessive caffeine intake, excessive alcohol use

Any time you have trouble falling asleep or staying asleep at night, your sleep cycle will be affected.

Limit Nightly Screen Use

NREM & REM: The Two Types Of Sleep

Weve discussed the effects of morning light on your circadian rhythm, and light in the evening works the same way. Household light, from both lamps and blue light emitted from laptops, smartphones and tablets, can trick your brain into thinking its still daytime, causing it to suppress melatonin production. Bright light wakes up your brain, Dr. Schwartz says.

Start dimming lights about two hours before bedtime and resist scrolling through social media in bed. If you work a night shift or need to use screens in the evenings, you can wear glasses that block blue light or install a blue light filter app on your device.

Maintaining a regular circadian rhythm is crucial for healthy sleep. If daytime drowsiness is interfering with your daily activities, you may have a sleep disorder. Schedule an appointment with the INTEGRIS Sleep Disorders Center of Oklahoma to discuss your symptoms and find a treatment plan to help you sleep better.

What Are Sleep Disorders

According to the American Sleep Association, at least 40 million Americans experience sleep disorders each year. Another 20 million have occasional sleep issues. These disorders cause sleep deprivation, leading to problems with work, school, driving and social activities.

There are more than 70 sleep disorders. A few, known as disruptive sleep disorders, lead to moving around or making sounds. Other sleep disorders involve food. And some sleep disorders overlap with psychiatric conditions. If you have problems with sleep or feel very tired, talk to your healthcare provider about a possible sleep disorder.

Some of the most common sleep disorders include:

    Regulating Your Circadian Rhythm

    Your circadian rhythm is the internal body clock that regulates sleep patterns. When your internal clock is disrupted by environmental or psychological factors, youre likely to suffer from fatigue, irritability, and depression.

    Fortunately, understanding how this 24-hour cycle works and what mental health problems and sleep habits affect it can get you back on the road toward deep sleep .

    Michelle Polizzi

    Rem Light Deep: How Much Of Each Stage Of Sleep Are You Getting

    Waking up tired, angry, or cranky? If you use a Fitbit Alta HR, Fitbit Charge 3Fitbit Versa, Fitbit Ionic, or Charge 4, your sleep data may soon be able to reveal why. By tapping into your nighttime heart rate and movement patterns, these devices will be able to estimate how much time you spend in light, deep, and rapid eye movement sleep. Pretty cool, right? Each of these stagesor sleep typesserve a different purpose, so understanding how much of each stage you log can help you identify and address sleep-related issues. Below, a breakdown of what you need to know about each sleep stage.

    Getting A Good Nights Sleep

    All stages of sleep are important, and transitioning between each is a vital part of achieving ample time in each stage. Its the balance of time spent in each sleep stage that is critical to feeling fully rested and refreshed, and to having the mental and physical energy to meet the requirements of the waking day. By creating habits and routines that promote healthy sleep, you help your body maintain the integrity of your own individual sleep schedule, which in turn benefits your long-term health.

    If youre having trouble sleeping, youre waking up often during sleep, or you feel that you simply never enter deep sleep during the night, its critical not to ignore it. Its easy to feel helpless when you spend hour after hour, for many nights in a row, hopelessly chasing sleep with no success. Dont give up. Taking steps to stay asleep with fewer interruptions, like using a white noise machine and proper temperature control, can ensure you pass through your sleep cycles smoothly and wake up feeling rested and refreshed.

    What Can Cause Circadian Rhythms To Become Out Of Sync

    When the SCN receives contradictory information, sleep rhythms can become desynchronized from day and night.

    A disrupted circadian rhythm is common in shift work, in which people follow an irregular sleep-wake cycle that may require staying awake at night or sleeping during the day. A disrupted circadian rhythm is also the cause of jet lag, which is when an individual’s body clock is not yet synchronized with the new local time. When these schedules interfere significantly with a person’s circadian rhythm, the person is considered to have an external circadian rhythm disorder.

    Certain medications, health conditions, and habits, such as using screens late at night, can also interfere with natural sleep cycles.

    Follow Good Sleep Hygiene

    Good sleep hygiene is essential to maintain a proper sleep-wake rhythm. As explained by the American Sleep Association, practicing good sleep hygiene means making healthy changes to your daily schedule in order to promote restful sleep.

    One example of good sleep hygiene is setting boundaries with technology in the bedroom. Since the blue light from electronics can disrupt your circadian rhythm, you might decide to stop using smartphones and tablets a few hours before bedtime. Additionally, you might decide to remove televisions, computers, and even smartphones from the room during sleep to help you create a more restful sanctuary.

    This is also important because it helps you associate your bedroom only with sleep. When youre constantly working on a laptop or scrolling through Facebook while lying in bed, your body will begin to associate that space with wakefulness, rather than sleep.

    What Is Rem Sleep

    When you enter REM sleep, brain activity increases again, meaning sleep is not as deep. The activity levels are like when youre awake. Thats why REM sleep is the stage where youll have intense dreams.

    At the same time, major muscles that you normally control cant move. In effect, they become temporarily paralyzed.

    Usually, REM sleep arrives about an hour and a half after you go to sleep. The first REM period lasts about 10 minutes. Each REM stage that follows gets longer and longer.

    The amount of REM sleep you experience changes as you age. The percentage of REM sleep:

    • Is highest during infancy and early childhood.
    • Declines during adolescence and young adulthood.
    • Declines even more as you get older.

    Alternative Sleep Cycles And Patterns:

    sleep and aging maria conley m d

    Monophasic sleep is just one cycle among many. Studies have shown that there are other, more pragmatic ways to get some shut eye. In 2001, historian Roger Ekirch published a seminal paper that suggested humans originally slept in two phases. His book, At Days Close: Night in Times Past, shows over 500 references to polyphasic sleep throughout history, from Homers Odyssey to modern tribes in Nigeria.

    Each of these alternate sleep cycles are polyphasic which means they involve multiple sleep phases each day.

    How Our Sleep Cycles Change During Our Lifespan

    Just as the amount of sleep someone needs changes depending on their age, so does their sleep cycle.

    Newborns, who typically sleep up to 18 hours a day, split their sleep time pretty evenly between REM and non-REM sleep, according to HealthyChildren.org, a website run by the American Academy of Pediatrics.

    Harvard Health Publishing says it takes people longer to fall asleep as they get older. The website cites a 2004 study on sleep, which found that 20-year-olds will take 16 minutes to fall asleep and sleep for 7.5 hours; 60-year-olds take 18 minutes to fall asleep and sleep for 6.2 hours; and 80-year-olds take 19 minutes to fall asleep and will sleep for 5.8 hours .

    Whats more, 20-year-olds spend 20 percent of their sleep time in slow-wave sleep, 60-year-olds spend 10 percent, and 80-year-olds spend just 7.5 percent of their sleep time in slow-wave sleep.

    According to the Cleveland Clinic, as we get older we spend more time in light sleep, and also experience more sleep disruptions throughout the night.

    In general, older people sleep less, have more fragmented sleep, and spend less time in stage 3 , and rapid eye movement sleep, than younger people, the Cleveland Clinic website explains.

    This poses a bit of a conundrum: Seniors generally spend less time sleeping than younger adults, even though elderly people need around the same amount of sleep .

    The Complete Guide To Your Sleep Cycle

    Going to bed each night might be the most relaxing part of the day. But while someone sleeps, their body and brain continue to work hard the brain isnt switched off by any means. When someone is asleep, they move through different stages of sleep to complete a full sleep cycle, which lasts around 90 minutes. When one cycle ends, the process repeats all over again and keeps going until their alarm goes off or they wake up naturally.

    Knowing how sleep cycles work can help people understand how much sleep they need, and why they sometimes wake up feeling awful and other times awaken naturally feeling refreshed, energized, and ready to face the day. Heres the lowdown on our bodys sleep cycles.

    What Happens During Non

    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. This can last for 10-25 minutes.

    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.

    Use Bright Light Therapy

    If youre struggling with seasonal affective disorder, bright light therapy can help get your circadian clock back on track. Since sunlight exposure is what regulates your circadian rhythm, exposure to artificial light can help a person get back to a normal sleep schedule. This is especially useful in places far north of the equator where long periods of darkness persist during the winter months.

    Light therapy is used to expose your eyes to intense but safe amounts of light for a specific and regular length of time. In many places, sunlight is not available at the proper time to be used as treatment, says the American Academy of Sleep Medicine.

    Where Can I Get More Information

    For information on other neurological disorders or research programs funded by the National Institute of Neurological Disorders and Stroke, contact the Institute’s Brain Resources and Information Network at:

    Office of Communications and Public LiaisonNational Institute of Neurological Disorders and StrokeNational Institutes of HealthBethesda, MD 20892 Publication No. 17-3440c

    NINDS health-related material is provided for information purposes only and does not necessarily represent endorsement by or an official position of the National Institute of Neurological Disorders and Stroke or any other Federal agency. Advice on the treatment or care of an individual patient should be obtained through consultation with a physician who has examined that patient or is familiar with that patient’s medical history.

    All NINDS-prepared information is in the public domain and may be freely copied. Credit to the NINDS or the is appreciated.

    What Controls Our Circadian Rhythm

    How does our body clock know what time of day it is? The circadian biological clock is controlled by a part of the brain called the Suprachiasmatic Nucleus , a group of cells in the hypothalamus that respond to light and dark signals. When our eyes perceive light, our retinas send a signal to our SCN. The SCN sets off a chain reaction of hormone production and suppression that affects body temperature, appetite, sleep drive, and more.

    Each morning, as sunlight creeps in, our body temperature begins to rise and cortisol is released, increasing our alertness and causing us to wake up. In the evening, as it becomes dark outside, melatonin levels rise and body temperature lowers. Melatonin stays elevated throughout the night, promoting sleep. As long as our eyes perceive light, the SCN responds by suppressing melatonin production. This explains why evening exposure to light, such as that from indoor light or electronic devices that emit blue light, such as a computer or television, make it harder to fall asleep.

    What Impacts Circadian Rhythms

    Circadian rhythms are impacted by both internal and external factors . Circadian rhythm-related sleep disorders that originate within the body are called intrinsic circadian sleep disorders. Those that originate from outside the body are often referred to as circadian rhythm disorders.


    As infants and children age, the sleep-wake schedule shifts, and the needed amount of sleep tapers off. Infants, for example, need between 12 to 16 hours of sleep each day, while school-aged children need nine to 12 hours. Adults should aim to get between seven to nine hours of restful sleep each night.

    Many teenagers experience a sleep-phase delay , in which their brain doesnt start producing melatonin until late in the evening. Late nights paired with early school wake-up times can take a significant toll on mental health and make it hard to stay focused.

    Blue Light Exposure

    Blue light waves are found in fluorescent and LED lights and electronic screens, such as phones, laptops, and television. Exposure to blue light waves at times when the brain should be producing melatonin, which is in the evening for most people, can halt the process and ultimately shift the circadian rhythm. As a result, blue light exposure can make falling asleep more difficult.

    Jet Lag and Daylight Saving Time

    Crossing two or more time zones can result in jet lag , a sleep-wake disorder that occurs when the body’s internal clock is aligned with the timezone of origin and doesnt match that of the new location.

    Sleep Hygiene Tips For Older Adults


    An easy way to improve sleep is by adopting sleep hygiene habits that strengthen the circadian rhythm and create a mental association between bed and sleep. To start sleeping better, experts recommend:

    • Keeping the bedroom cool, dark, and quiet
    • Avoiding and limiting alcohol, caffeine, and tobacco after lunch
    • Avoiding liquids and large meals before bed
    • Keeping naps to a maximum of 30 minutes
    • Eating a healthy diet with plenty of fruits and vegetables
    • Getting daily exercise, preferably outside
    • Turning off the TV and other screens an hour before bed
    • Keeping the bed for sleeping and sex only
    • Getting out of bed and doing something else if you cant sleep

    You should also make it a priority to treat any underlying sleep disorders or other conditions such as chronic conditions such as diabetes, heart failure, or prostate disorders. Talk to your doctor to see if you can adjust your medication schedule to minimize the effects on your sleep. In the short term, your doctor may prescribe melatonin supplements or cognitive behavioral therapy for insomnia to help re-establish a healthy sleep pattern.

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    What Is Your Circadian Rhythm And Why Is It Important

    There are few things better than a good nights sleep, but many of us struggle to catch enough Zs. If you struggle to fall asleep and wake up at a set time, or catch yourself yawning throughout most of the day, your circadian rhythm could be off.

    Were here to help you understand not only how it works, but how you can get your circadian rhythm back on track for healthy sleep. Dr. Jonathan Schwartz of the INTEGRIS Sleep Disorders Center of Oklahoma lends his expertise to help us get to the bottom of the clock that keeps your sleep-wake cycle functioning efficiently.

    Neurotransmitters And Your Sleep

    Some neurotransmitters help your body recharge while you sleep. They can even help you to remember things that you learned, heard, or saw while you were awake. The neurotransmitter acetylcholine is at its strongest both during REM sleep and while you are awake. It seems to help your brain keep information gathered while you are awake. It then sets that information as you sleep. So if you study or learn new information in the hours before bed, “sleeping on it” can help you remember it.

    Other neurotransmitters may work against you as you sleep. Abnormalities with the neurotransmitter dopamine may trigger sleep disorders such as restless legs syndrome.

    Even losing just 1 hour of sleep over a few days can have an effect. It can lead to a decrease in performance, mood, and thinking. Getting regular, adequate amounts of sleep is important. It can help you feel awake and refreshed during the day. It can also help you feel relaxed and sleepy at night. This helps make you ready for a long, restful night of sleep. 

    Delayed Sleep Phase Disorder

    Delayed Sleep-Phase Disorder , also called Delayed Sleep Phase Syndrome , is a circadian sleep disorder in which the individual’s internal body clock is delayed with respect to the external day/night cycle.

    A person with DSPD naturally falls asleep late at night, typically between 1:00 am and 6:00 am, and awakens in the late morning or in the afternoon. There is a striking inability to fall asleep at an earlier, more typical bedtime. As a result, many people with DSPD have been labeled as insomniacs. But if such a person is allowed to follow his internal body clock, he generally has no problems with either falling asleep or waking naturally.

    However, if he ignores his internal clock and attempts to live on a normal schedule, he finds himself unable to fall asleep until very late, but is forced to wake up early nonetheless. Despite being tired all day, he finds himself unable to fall asleep any earlier the next night.DSPD sufferers therefore differ from typical night owls who prefer to stay up late at night but can sleep at earlier times when they desire. A person with DSPD has no choice as to what time sleep onset comes.

    Thus DSPD has two essential components: one is the body’s daily cycle, which is later than normal; the other is the difficulty or even inability to shift one’s schedule to an earlier time.

    How Do I Regulate My Circadian Rhythm

    You can entrain your circadian clock to a certain extent by consistently providing your body with certain cues at the right times. These signals help train your body to recognize when you would like to sleep and when you would prefer to be awake. Some strategies include:

    • Setting your alarm at the same time every day
    • Receiving exposure to bright light soon after you wake up
    • Eating a healthy diet and avoiding large meals at night
    • Exercising regularly
    • Limiting naps, especially late in the day
    • Avoiding caffeine, alcohol, and tobacco in the evening
    • Turning off screens at least one hour before bed
    • Reserving the bedroom for sleep and sex only
    • Keeping the bedroom cool, dark, and quiet

    Everyone reacts differently to these cues, so you may need to experiment and see what works for you. Talk to your doctor if your sleep clock is still acting up after trying these sleep hygiene tips. A doctor can help pinpoint the source of any sleep problems and offer additional treatment options to help you sleep better.


    Why Is Sleep Important

    The physiological changes that occur during sleep help to regulate different bodily functions, including:

    Brain function: Each distinct sleep stage helps to restore cells in the brain and optimize its daytime performance. The brain will essentially reorganize itself and create new pathways to help you learn new information and consolidate memories. At the same time, it flushes out “toxic” byproducts that can negatively impact brain health and performance.

    Seek Professional Help If Needed

    If conventional home remedies and sleep aids dont seem to be mitigating the problem, it may be worth seeking help from a medical professional. Sleep disorders like insomnia, sleep paralysis, and narcolepsy are serious conditions and should not be ignored. Sleep is vital to your health, and successfully sleeping through the night and completing your sleep cycles is necessary for any healthy lifestyle.

    The four stages of sleep, brain waves, REM sleepit can sound pretty complicated. Luckily, your body is able to naturally handle these processes every day. If it needs a little guidance getting on the right rhythm, SleepScore can help.


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