Rapid eye movement

Rapid eye movement (REM) sleep is the normal stage of sleep characterized by rapid movements of the eyes. REM sleep is classified into two categories: tonic and phasic. Criteria for REM sleep include not only rapid eye movements, but also low muscle tone and a rapid, low voltage EEG -- these features are easily discernible in a polysomnogram, the sleep study typically done for patients with suspected sleep disorders.

REM sleep in adults typically occupies 20-25% of total sleep, lasting about 90-120 minutes. During a normal night of sleep, we usually experience about 4 or 5 periods of REM sleep; they are quite short at the beginning of the night and longer at the end. It is common to wake for a short time at the end of a REM phase. The relative amount of REM sleep varies considerably with age. A newborn baby spends more than 80% of total sleep time in REM (see also Active Sleep). During REM, the summed activity of the brain's neurons is quite similar to that during waking hours; for this reason, the phenomenon is often called paradoxical sleep. Most of our vividly recalled dreams occur during REM sleep. This also means that there are no dominating brain waves during REM sleep.

REM sleep is so physiologically different[citation needed] from the other phases of sleep that the others are collectively referred to as non-REM sleep.

Physiologically, certain neurons in the brain stem, known as REM sleep-on cells (located in the pontine tegmentum), are particularly active during REM sleep, and are probably responsible for its occurrence. The release of certain neurotransmitters, the monoamines (norepinephrine, serotonin and histamine), is completely shut down during REM. This causes REM atonia, a state in which the motor neurons are not stimulated and thus the body's muscles don't move. Lack of such REM atonia causes REM Behavior Disorder; sufferers act out the movements occurring in their dreams.

Heart rate and breathing rate are irregular during REM sleep, again similar to the waking hours. Body temperature is not well regulated during REM. Erections of the penis (Nocturnal Penile Tumescence or NPT) is an established accompaniment of REM sleep and is used diagnostically to determine if male erectile dysfunction is of organic or psychological origin. Clitoral enlargement, with accompanying vaginal blood flow and transudation (i.e. lubrication) is also present during REM.

The eye movements associated with REM are generated by the pontine nucleus with projections to the superior colliculus and are associated with PGO (pons, geniculate, occipital) waves.


REM sleep disorders
M sleep can occur within about 90 minutes, but in those with a sleep onset REM period, it may be as little as 15-25 minutes. This is considered a sign of narcolepsy.


Theories about the function(s) of REM sleep
The function of REM sleep is not well understood; several theories have been advanced.
According to one theory, certain memories are consolidated during REM sleep. Numerous studies have suggested that REM sleep is important for consolidation of procedural and spatial memories. (Slow-wave sleep, part of non-REM sleep, appears to be important for declarative memories.) However, in people that have no REM sleep (because of brain damage), memory functions are not measurably affected.

Another theory suggests that monoamine shutdown is required so that the monoamine receptors in the brain can recover to regain full sensitivity. Indeed, if REM sleep is repeatedly interrupted, the person will "make up" for it with longer REM sleep at the next opportunity. Acute REM sleep deprivation can improve certain types of depression, and depression appears to be related to an imbalance of certain neurotransmitters. Most antidepressants selectively inhibit REM sleep due to their effects on monoamines. However, this effect decreases after long-term use.

According to a third theory, known as the Ontogenetic Hypothesis of REM sleep, this sleep phase (also known as Active Sleep in neonates) is particularly important to the developing brain, possibly because it provides the neural stimulation that newborns need to form mature neural connections and for proper nervous system development. Studies investigating the effects of Active Sleep deprivation have shown that deprivation early in life can result in behavioral problems, permanent sleep disruption, decreased brain mass and result in an abnormal amount of neuronal cell death. REM sleep is necessary for proper central nervous system development. Further supporting this theory is the fact that the amount of REM sleep decreases with age, as well as the data from other species


REM sleep in other animals
REM sleep occurs in all mammals and birds. It appears that the amount of REM sleep per night in a species is closely correlated with the developmental stage of newborns. The platypus for example, whose newborns are completely helpless and undeveloped, has 8 hours of REM sleep per night; in dolphins, whose newborns are almost completely functional at birth, almost no REM sleep exists after birth.


REM sleep suppressants
Various drugs, including alcohol, benzodiazepines, and antidepressants are known to suppress REM sleep.

Sleeping Disorder?

How much sleep do you get each night? If you are sleep for less than 7 hours a night, you may be suffering from a lack of sleep. Many people can function on less than 7 hours of sleep, but they are not at their best. Over many weeks or years, this lack of sleep interacts with the body and can worsen health conditions. About 95% of the population needs between 7 and 9 hours of sleep each night. Sure, there are a lucky few who physically need less -- but that is a rare situation. If you are not feeling energetic during the day, add hours to your sleep and see if it makes a difference.

How much sleep we need depends on what is happening in our bodies. The rapid growth of infancy and adolescence and the demands on the body during pregnancy mean more sleep. Contrary to the common sleep myth, older adults need just as much sleep as younger ones. Here is a list of sleep needs by group:

Infants: 16 hours a day
Young Children: 10-14 hours a day
Teenagers: 9 hours a day
Pregnant women: several extra hours a day in the first trimester
Adults: 7 to 9 hours a day
Older Adults: 7 to 9 hours a day
Finding Your 'Sleep Need'

A person should be alert and awake throughout the day. Some signs that you are not getting enough quality sleep include:
- Feeling tired during the day
- Falling asleep within 5 minutes of lying down
- Experiencing “microsleeps” or brief “nodding off” episodes
- Sleep Quality and Sleep Quantity

If you find that you are not getting enough sleep, there are two things to look at: the amount of time you spend sleeping and the quality of your sleep. Sleep Time: If you spend less than 7 hours in bed (asleep) each night, you will most likely have a sleep deficit.

You could also be spending enough time in bed, but have trouble falling asleep quickly. Learning good sleep habits can help you fall asleep faster and get more sleep in the same amount of time. Sleep Quality: If your sleep is interrupted, if you wake up several times a night or if you toss and turn, your sleep quality may be poor. You need two kinds of sleep each night – deep sleep (sleep stage 3 and 4), which makes you feel refreshed, and REM sleep, which we don’t fully understand, but we know you need it. Developing better sleep habits can help with sleep quality.

Sleep Disorders and Problems
There are also many types of sleep disorders that can impact your sleep. The two most common sleep disorders are insomnia and sleep apnea. Less common sleep disorders include narcolepsy and restless leg syndrome (RLS). These disorders can be caused by health conditions, medications, anxiety and other factors. Narcolepsy is a rare disease that affects between 25 and 50 people per 100,000 people. RLS is more common. However, several clinical conditions are associated with RLS, such as iron deficiency, chronic kidney diseases, pregnancy, polyneuropathy, type 2 diabetes mellitus and multiple sclerosis. Many sleep disorders can be treated through a combination of changing your sleep habits and medications. Sleep apnea generally requires treatment with positive airway pressure. Many people over 65 have trouble sleeping because of health conditions.


Understanding Sleep
Sleep is a major part of our lives. However, researchers and doctors understand little about sleep and what it does for us. What we do know is that sleep has many health benefits and getting a good night’s sleep is the key to feeling energized every day. Understanding sleep can help you improve your health and may even extend your life.


Sleep Habits
Sleep habits are the key to getting a good night’s sleep. We can either train ourselves to fall asleep quickly every night, or we can train ourselves to lie awake in bed through bad habits. Exercise, caffeine, stress and other factors can influence the quantity and quality of our sleep. Changing your sleep habits can lead to greatly improve sleep quality and quantity.


Sleep Disorders and Sleep Problems
If changing your sleep habits doesn’t help, you may have a sleep disorder.
The most common sleep disorders include:
- Insomnia
- Sleep apnea
- Restless Legs Syndrome
- Narcolepsy


The following situations can interfere with your daily Zzzzs as well:
- Jet lag
- Working the night shift
- Nighttime driving
- Snoring


leep Diagnosis and Treatment
You may have a sleep disorder if it takes you more than 30 minutes to fall asleep each night, you are tired during the day and you do not feel rested. If you think you might have a sleep problem, try these three steps:
Improve Your Sleep Habits: Make big changes in your sleep habits for 2 to 3 weeks to see if you can figure out what is causing you to sleep poorly.

Keep a Sleep Diary: Track your sleep and other behaviors for several days to make connections between your daily activities and your sleep quality.

Find a Sleep Center and Doctor: If your sleep doesn’t improve, take your sleep diary to a sleep center or sleep doctor near you for more testing.
Sleep Needs

Each individual’s sleep need varies. For the majority of adults, the daily sleep need is between 7 and 9 hours. Some people need even more than 9 hours and others need less than 7, but this is rare. If you are awake and alert during the day and feel satisfied with your sleep, then you are getting enough sleep.


Sleep and Aging
There is a myth that people need less sleep as they age. This is simply not true: Older adults need 7 to 9 hours of sleep every night. However, good sleep is harder to get as we age because of health conditions, medications and other reasons. Protecting your sleep as you age will give you more energy and better health.
Sleep Myths

Other sleep myths include misunderstandings about the benefit of sleeping in to “catch up” on sleep, sleep in children, the benefits of napping and more. Clearing up these sleep myths will help you to make better decisions about your daily sleep habits.


Sleep Benefits
While we know that sleep makes us feel refreshed, there are many health and other benefits to a good night’s sleep. These include improving heart health, improving your memory and maybe even preventing cancer. Other benefits include improving your skin and helping you concentrate.


Napping
Napping can be a great way to increase your sleep and improve your energy. Napping has been shown to increase productivity and even protect against heart disease. Napping strategies will help you take effective, short naps and then go back to your day recharged.


Sleep Biology
Sleep is a complicated process consisting of five stages. These stages include falling asleep (stage 1), brain slow-down (stage 2), deep sleep (stages 3 and 4) and rapid eye movement (REM). In each stage, the brain and body act differently. During the night, we cycle through all these stages approximately every 100 minutes.
Circadian Rhythms

Throughout the day the body makes changes in various hormone levels. Some of these changes, known as circadian rhythms, control our wake/sleep cycle. By getting enough exposure to bright light and following other behavioral suggestions, we can work with our circadian rhythms help ourselves fall asleep fast every night.
Dreaming and Sleep

Of course, dreaming is one of the strangest and least understood parts of sleep. Dreams seem to be important in creating memories out of the day’s events and solidifying learning. Dreams can be extremely vivid, interesting and potentially meaningful to the dreamer.



Master Napping
Napping, if done effectively, can revitalize you day in a way that no cup of coffee ever can. If done incorrectly, napping can ruin your night sleep and leave you feeling groggy and more tired. Here are a sample of some napping tips:
- nap for 20 minutes
- use an eye pillow
- don't nap within 3 hours of bedtime
- try to nap in the same place each time


Impaired Sleep Quality And Allergic Rhinitis Linked
Patients with allergic rhinitis, such as that caused by hay fever and other allergies, have more difficulty sleeping and more sleep disorders than those without allergies, according to a report in the September 18 issue of Archives of Internal Medicine, a theme issue on sleep.


The Health Effects of Marijuana
Although legalization activists and many marijuana users believe smoking pot has no negative effects, scientific research indicates that marijuana use can cause many health problems. Marijuana is the most commonly used illicit drug in the United States. When smoked, it begins to effect users almost immediately.


Childhood Obesity and Sleep Apnea
Childhood obesity is on the rise, and along with the obesity comes other problems --- heart disease, type 2 diabetes and high blood pressure. Another problem, long thought to be a disorder of older, overweight males, is sleep apnea. Sleep apnea can cause both physical and mental problems