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Sleep FAQs

Reviewed by Melissa Conrad Stöppler, MD

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Q:Who requires 9 hours of sleep per night?

A:School-aged children and teens. Sleep needs vary from person to person, and they change throughout the lifecycle. Most adults need 7-8 hours of sleep each night. Newborns, on the other hand, sleep between 16 and 18 hours a day, and children in preschool sleep between 10 and 12 hours a day. School-aged children and teens need at least 9 hours of sleep a night.

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Q:There are how many stages of sleep?

A:Five. There are five stages of sleep. During the first four stages of sleep, the muscles of the eyes are relaxing. These stages are collectively referred to as nonrapid eye movement (nonREM) sleep. The last stage of sleep is associated with increased contraction of the eye muscles. As a result, the fifth stage of sleep (when eye movement is active) is called rapid eye movement sleep or REM sleep.

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Q:Sleep apnea is America's most common sleep disorder. True or False?

A:False. Insomnia is the most common sleep disorder in the U.S., affecting a third of adults at some point in life. Insomnia is defined as the complaint (or perception) of inadequate or poor-quality sleep because of one or more of the following: difficulty falling asleep; waking up frequently during the night with difficulty returning to sleep; waking up too early in the morning; or unrefreshing sleep. Insomnia is not defined by the number of hours of sleep a person gets or how long it takes to fall asleep. Individuals vary normally in their need for, and their satisfaction with, sleep. Insomnia may cause problems during the day, such as tiredness, a lack of energy, difficulty concentrating, and irritability.

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Q:Sleepwalking, which is characterized by walking during sleep, may also include what other activities?

A:Driving a car, moving furniture and sitting up and appearing awake may occur during an episode of sleepwalking. Sleepwalking is characterized by a complex behavior (such as walking) occurring while asleep. The sleepwalking activity may include simply sitting up and appearing awake (while actually still asleep) and getting up and walking around. Sleepwalking may include other complex activities such as: moving furniture; going to the bathroom; dressing and undressing, and similar activities. Some people even drive cars while actually asleep. The episode can be very brief (a few seconds or minutes) or can last for 30 minutes or longer.

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Q:What are possible symptoms of sleep deprivation?

A:Weight gain and poor hand-eye coordination are possible symptoms of sleep deprivation. There are two issues at work with sleep and weight gain. The first is intuitive: If you're up late, the odds are greater that you're doing some late-night snacking. The other reason involves what's going on biochemically when you're sleep deprived. Hormones that affect appetite take over, making you hungrier the next morning. These hormones also make you feel not as full after eating. Many studies make it clear that sleep deprivation is dangerous. Sleep-deprived people who are tested by using a driving simulator or by performing a hand-eye coordination task perform as badly as or worse than those who are intoxicated.

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Q:What is another term for sleep paralysis?

A:Hypnogogic sleep paralysis and hypnopompic sleep paralysis. Sleep paralysis occurs when a person passes between stages of wakefulness and sleep, and causes a feeling of being conscious but unable to move. If it occurs while you are falling asleep, it's called hypnagogic or predormital sleep paralysis. If it happens as you are waking up, it's called hypnopompic or postdormital sleep paralysis. During these transitions, you may be unable to move or speak for a few seconds up to a few minutes. Some people may also feel pressure or a sense of choking.

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Q:What is a circadian rhythm?

A:A circadian rhythm refers to a 24-hour period of time. The word "circadian" is a 20th-century invention. It was coined in 1959 from the Latin "circa" (around) + "diem" (a day).Circadian refers to events occurring within a 24-hour period, in the span of a full (24-hour) day, as in a circadian rhythm. Circadian rhythmicity is a fundamental property possessed by all organisms. These rhythms are driven by an internal time-keeping system commonly referred to as an internal clock.

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Q:Which mental illness has the strongest link to insomnia?

A:The most common sleep disorder, insomnia, has the strongest link to depression. In a 2007 study of 10,000 people, those with insomnia were five times as likely to develop depression as those without. In fact, insomnia is often one of the first symptoms of depression. Insomnia and depression feed on each other. Sleep loss often aggravates the symptoms of depression, and depression can make it more difficult to fall asleep. On the positive side, treating sleep problems can help depression and its symptoms, and vice versa.

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Q:People need less sleep as they grow older. True or False?

A:False. Even though sleep needs can vary throughout the lifecycle, adults (even older adults) still require an average of 7-8 hours of sleep per night. As we get older, we don't need less sleep, but we often get less sleep. That's because our ability to sleep for long periods of time and to get into the deep restful stages of sleep decreases with age. Older people have more fragile sleep and are more easily disturbed by light, noise, and pain. They also may have medical conditions that contribute to sleep problems. Going to bed at the same time every night and getting up at the same time every morning, getting exposure to natural outdoor light during the day, and sleeping in a cool, dark, quiet place at night may help. By age 75, for many reasons, some people may find they are waking up several times each night. But, no matter what your age, talk to a doctor if your sleep patterns change.

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Q:Breathing pauses, gasps, shallow breaths, and airway collapse during sleep indicate what condition?

A:Breathing pauses, gasps, shallow breaths, and airway collapse during sleep indicate sleep apnea. There are three types of sleep apnea: central sleep apnea (CSA); obstructive sleep apnea (OSA), and mixed sleep apnea (both central sleep apnea and obstructive sleep apnea). During sleep, the brain instructs the muscles of breathing to take a breath. Central sleep apnea (CSA) occurs when the brain does not send the signal to the muscles to take a breath, and there is no muscular effort to take a breath. Obstructive sleep apnea (OSA) occurs when the brain sends the signal to the muscles and the muscles make an effort to take a breath, but they are unsuccessful because the airway becomes obstructed and prevents an adequate flow of air. Mixed sleep apnea, occurs when there is both central sleep apnea and obstructive sleep apnea.

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Q:Treatments for insomnia can include sleep aids AND stimulants. True or False?

A:True. Self-treatment of insomnia with over-the-counter (OTC) drugs is advisable only for transient or short-term insomnia. OTC sleep aids should only be used for a short period of time in conjunction with changes in sleeping habits. Chronic use of these drugs may result in dependence on them. This creates a situation in which sleep is not possible unless the drug is used. Chronic insomnia should be evaluated by a physician. Persons with insomnia often suffer from fatigue as a result of sleep deprivation. Stimulant products are frequently used in an attempt to offset fatigue and other unpleasant side effects that can accompany a lack of sleep. (These products are also used by persons who need to stay awake for longer periods of time than is normal for them, such as school examinations or long distance driving.) However, the use of stimulant products can also cause insomnia, leading to a counterproductive effort to deal with sleep deprivation.

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Q:What is the common term for high-level anxiety or terror while sleeping?

A:Nightmares. Nightmares refer to complex dreams that cause high levels of anxiety or terror. In general, the content of nightmares revolves around imminent harm being caused to the individual. Nightmares can occur multiple times in a given night, or one might experience them very rarely. Individuals may experience the same dream repeatedly, or they may experience different dreams with a similar theme. When individuals awaken from nightmares, they can typically remember them in detail. Upon awakening from a nightmare, individuals typically report feelings of alertness, fear, and anxiety.

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Q:What are complications of sleep deprivation?

A:Memory problems and depression, A weakened immune system and Increased pain perception. The consequences of too little sleep can include memory problems, depression, a weakening of your immune system, increasing your chance of becoming sick and an increase in perception of pain.

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Q:Humans’ biological clocks have how many daily periods of sleepiness?

A:Two. Our bodies are programmed by our biological clock to experience two natural periods of sleepiness during the 24-hour day, regardless of the amount of sleep we've had in the previous 24 hours. The primary period is between about midnight and 7:00 a.m. A second period of less intense sleepiness is in the mid-afternoon, between about 1:00 and 3:00. This means that we are more at risk of falling asleep at the wheel at these times than in the evening--especially if we haven't been getting enough sleep

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Q:Sleep disorders and chronic sleep loss can put you at risk for diseases and conditions such as…

A:Heart disease, heart attack, and heart failure. Sleep deprivation can lead to serious problems. Sleep disorders and chronic sleep loss can put you at risk for heart disease, heart attack, heart failure, irregular heartbeat (arrhythmia), high blood pressure, stroke and diabetes.

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Q:Drowsy driving is similar to driving under an intoxicating influence. True or False?

A:True. Drowsiness can slow reaction time as much as driving drunk. The National Highway Traffic Safety Administration estimates that fatigue is a cause in 100,000 auto crashes and 1,500 crash-related deaths a year in the U.S. The problem is greatest among people under 25 years old.

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