Skip to content

Sleep Disorders Health Center

Sleep Disorders Dictionary

Font Size
A
A
A

Here are definitions of sleep-related terms:

 

Recommended Related to Sleep Disorders

Too Sleepy for Sex?

Too tired for sex? Join the club. Up to 50% of U.S. adults skip or avoid sex because they're too tired, recent polls show. It’s no wonder. The workday can extend long into the night, many couples have children and pets to tend to, and everyone has diversions that tempt their attention away from their partners -- and from sleep. "We’re a 24/7 society. We're burning the candle at both ends -- most of us -- so we are tired," says William Kohler, MD, director of Florida Sleep Medicine outside...

Read the Too Sleepy for Sex? article > >

Cataplexy: Symptom of narcolepsy; consists of a sudden loss of muscle tone that leads to feelings of weakness and a loss of voluntary muscle control.

Central sleep apnea: Sleep disorder in which the airway is not blocked, but the brain fails to signal the muscles to breathe.

Chronotherapy: A behavioral technique in which bedtime is gradually adjusted; used in cases when the patient's sleep-wake pattern is out of synch with the external environment.

Circadian rhythms: Biological rhythms that include the internal clock which influences when, how much, and how well people sleep.

Cognitive therapy: In some cases of insomnia, this therapy includes interventions that are meant to help people identify and correct inappropriate thoughts and beliefs that may contribute to their sleep problems.

CPAP (continuous positive airway pressure): A device that is an effective treatment for sleep apnea patients; delivers air into airways through a specially designed face or nasal mask or pillows.

Mixed sleep apnea: A combination of central sleep apnea and obstructive sleep apnea.

Multiple sleep latency test (MSLT): Test that assesses the severity of sleepiness by measuring the speed of falling asleep.

Narcolepsy: A neurological condition in which people experience excessive daytime sleepiness, cataplexy, sleep paralysis, hallucinations, and intermittent, uncontrollable sleep attacks during the day.

Non 24-hour sleep wake disorder: A circadian rhythm disorder in which the sleep-wake pattern does not conform to the usual 24-hour cycle.

Non-Rapid Eye Movement (NREM) sleep: One of the two basic states of sleep; consists of stages 1, 2 (light sleep) and 3, 4 (deep sleep).

Obstructive sleep apnea (OSA): The most common kind of sleep apnea. It is caused by a blockage of the upper airway that causes the body to struggle to get air.

Periodic Limb Movement Disorder (PLMD): A disorder in which rhythmic jerking of the legs interrupts sleep, causing insomnia and/or excessive daytime sleepiness.

Parasomnias: Abnormal behaviors during sleep that interrupt sleep and can result in injury, insomnia, and/or excessive daytime sleepiness.

Polysomnography: A test that records aspects of sleep (for example, the amount of NREM and REM sleep, number of arousals) and a variety of body functions during sleep, including breathing patterns, heart rhythms, and limb movements.

Today on WebMD

fatigued senior woman
We’ve got 10 tips to show you how
Man snoring in bed
Know your myths from your facts.
 
Young woman sleeping
What do your dreams say about you?
woman eith hangover
It’s common, and really misunderstood.
 

Is This Normal? Get the Facts Fast!

How Many Hours Did You Sleep Last Night?
Is that amount of sleep typical for you?
Did you get enough sleep to feel alert today and function at your best?

Get the latest Sleep Disorders newsletter delivered to your inbox!


or
Answer:
0-6
7-8
9+

Your level is currently

You say you are able to function well with fewer than seven hours of sleep. Some people say they can function on four to six hours of sleep each night, but research shows that adults who get fewer than seven hours of sleep — whether for just one night or over the course of days, weeks, or months — have more difficulty concentrating and more mood problems than people who sleep seven to nine hours.

Since you usually get too little sleep, please talk to your doctor about your sleep patterns. Poor quality sleep can affect many areas of your life and health, and your doctor may be able to help you if you have insomnia or other conditions affecting your sleep.

Sleep deprivation can have both short- and long-term consequences. Learn more about the health consequences of sleep loss. If you're concerned about having trouble falling asleep or staying asleep, assess your risk for a sleep disorder.

It's not surprising you feel that you're not functioning at your best today. Some people say they can function on four to six hours of sleep each night, but research shows that adults who get fewer than seven hours of sleep — whether for just one night or over the course of days, weeks, or months — have more difficulty concentrating and more mood problems than people who sleep seven to nine hours.

Since you usually get too little sleep, please talk to your doctor about your sleep patterns. Poor quality sleep can affect many areas of your life and health, and your doctor may be able to help you if you have difficulty sleeping, have insomnia, or have other sleep disorders.

Learn more about the health consequences of sleep loss. If you're concerned about having trouble falling asleep or staying asleep, assess your risk for a sleep disorder.

It's not surprising you feel that you're not functioning at your best today. Some people say they can function on four to six hours of sleep each night, but research shows that adults who get fewer than seven hours of sleep — whether for just one night or over the course of days, weeks, or months — have more difficulty concentrating and more mood problems than people who sleep seven to nine hours.

It's good that you usually do get more sleep, since sleep deprivation can have both short- and long-term consequences. Learn more about the health consequences of sleep loss. And if you're concerned about having trouble falling asleep or staying asleep, assess your risk for a sleep disorder.

You say you are able to function well with fewer than seven hours of sleep. Some people say they can function on four to six hours of sleep each night, but research shows that adults who get fewer than seven hours of sleep — whether for just one night or over the course of days, weeks, or months — have more difficulty concentrating and more mood problems than people who sleep seven to nine hours.

It's good that you usually do get more sleep because sleep deprivation can have both short- and long-term consequences. Learn more about the health consequences of sleep loss. And if you're concerned about having trouble falling asleep or staying asleep, assess your risk for a sleep disorder.

It's not surprising you feel that you're not functioning at your best today. Some people say they can function on four to six hours of sleep each night, but research shows that adults who get fewer than seven hours of sleep — whether for just one night or over the course of days, weeks, or months — have more difficulty concentrating and more mood problems than people who sleep seven to nine hours.

Since you usually get less sleep, please talk to your doctor about your sleep patterns. Poor quality sleep can affect many areas of your life and health, and your doctor may be able to help you if you have difficulty sleeping or have insomnia or other sleep disorders.

Learn more about the health consequences of sleep loss. If you're concerned about having trouble falling asleep or staying asleep, assess your risk for a sleep disorder.

It's wonderful that you got a good night's sleep last night. Many people struggle to do so. Having a good sleep routine often is the key to getting the quality sleep night after night that your body needs for optimal health. Whether your sleep routine involves taking a warm bath, reading a book, or meditating, it's important to keep your bedtime and routine consistent every night and wake up around the same time every morning.

Click here to read more about the importance of sleep. If you're concerned about having trouble falling asleep, staying asleep, or sleeping too much, assess your risk for a sleep disorder.

It's unfortunate you're not functioning at your best today. You say you had a good quantity of sleep last night, but maybe the quality of your sleep is not as good as it could be? Having a good sleep routine — including a consistent bedtime and wake time — often is the key to getting the quality sleep night after night that your body needs for optimal health. Since you usually sleep this amount, if you often aren't feeling your best, you should consider talking to your doctor. Could you have an underlying condition? Are you feeling anxious or depressed? Have you taken medication that disrupted your sleep? Do you or could you have sleep apnea? Or do you naturally require a little bit more sleep?

Although sleep is crucial for optimal health, some research suggests that sleeping too much can also have negative consequences. Learn more about sleep. If you're concerned about having trouble falling asleep, staying asleep, or sleeping too much, assess your risk for a sleep disorder.

It's unfortunate you're not functioning at your best today. You say you had a good quantity of sleep last night, but maybe the quality of your sleep is not as good as it could be? Having a good sleep routine — including a consistent bedtime and wake time — often is the key to getting the quality sleep night after night that your body needs for optimal health. Since you usually sleep longer, if you often aren't feeling your best, you should consider talking to your doctor. Could you have an underlying condition? Are you feeling anxious or depressed? Have you taken medication that disrupted your sleep? Do you or could you have sleep apnea? Or do you naturally require a little bit more sleep?

Although sleep is crucial for optimal health, some research suggests that sleeping too much can also have negative consequences. Learn more about sleep. If you're concerned about having trouble falling asleep, staying asleep, or sleeping too much, assess your risk for a sleep disorder.

It's wonderful that you got a good night's sleep last night. Many people struggle to do so. Having a good sleep routine often is the key to getting the quality sleep night after night that your body needs for optimal health. Whether your sleep routine involves taking a warm bath, reading a book, or meditating, it's also important to keep bedtime consistent and wake up around the same time every morning.

Although sleep is crucial for optimal health, some research suggests that sleeping too much can have negative consequences. Learn more about sleep. If you're concerned about having trouble falling asleep, staying asleep, or sleeping too much, assess your risk for a sleep disorder.

It's unfortunate you're not functioning at your best today. You say you had a good quantity of sleep last night, but maybe the quality of your sleep is not as good as it could be? Having a good sleep routine — including a consistent bedtime and waking up at the same time — often is the key to getting the quality sleep night after night that your body needs for optimal health.

Since you usually get less sleep, please talk to your doctor about your sleep patterns. Poor quality sleep can affect many areas of your life and health, and your doctor may be able to help you if you have insomnia, another sleep disorder, or conditions affecting your sleep.

Learn more about the health consequences of sleep loss. If you're concerned about having trouble falling asleep or staying asleep, assess your risk for a sleep disorder.

It's wonderful that you got a good night's sleep last night. Many people struggle to do so. Having a good sleep routine often is the key to getting the quality sleep night after night that your body needs for optimal health.

Since you usually get less sleep, talk to your doctor about your sleep patterns. Poor quality sleep can affect many areas of your life and health, and your doctor may be able to help you if you have insomnia or another sleep disorder or conditions affecting your sleep.

Learn more about the health consequences of sleep loss. If you're concerned about having trouble falling asleep or staying asleep, assess your risk for a sleep disorder.

SOURCES:

Centers for Disease Control and Prevention (CDC). Effect of short sleep duration on daily activities--United States, 2005-2008. MMWR Morb Mortal Wkly Rep 2011; 60:239.

Carskadon, MA, Dement, WC. Normal Human Sleep: An Overview. In: Principles and Practices of Sleep Medicine, Fifth, Kryger, MH, Roth, et al. (Eds), Elsevier Saunders, St. Louis, MO 2011. p.16.

Harvard University: "Sleep, Performance, and Public Safety."

Did You Know Lifestyle Choices
Impact Your Sleep?

Use the WebMD Sleep Tracker to track
your ZZZs over time.

Get Started

This tool is intended only for adults 18 and older.

Start Over

Step:  of 

Young woman sleeping
Quiz
Cannot sleep
Video
 
child sitting in bed
Article
Woman with insomnia
Quiz
 
nurse sleeping
ARTICLE
Foods That Help Or Harm Your Sleep
SLIDESHOW
 
Insomnia 20 Tips For Better Sleep
Slideshow
Pain at Night
ARTICLE