A sleep study is a test that records the activity of the body during

sleep Sleep is a state of reduced mental and physical activity in which consciousness is altered and certain Sensory nervous system, sensory activity is inhibited. During sleep, there is a marked decrease in muscle activity and interactions with th ...

. There are five main types of sleep studies that use different methods to test for different sleep characteristics and disorders. These include simple sleep studies,

polysomnography Polysomnography (PSG) is a multi-parameter type of sleep study and a diagnostic tool in sleep medicine. The test result is called a polysomnogram, also abbreviated PSG. The name is derived from Greek and Latin roots: the Greek πολύς ('' ...

, multiple sleep latency tests (MSLTs), maintenance of wakefulness tests (MWTs), and home sleep tests (HSTs). In medicine, sleep studies have been useful in identifying and ruling out various

sleep disorder A sleep disorder, or somnipathy, is a medical disorder affecting an individual's sleep patterns, sometimes impacting physical, mental, social, and emotional functioning. Polysomnography and actigraphy are tests commonly ordered for diagnosing sle ...

s. Sleep studies have also been valuable to psychology, in which they have provided insight into brain activity and the other physiological factors of both sleep disorders and normal sleep. This has allowed further research to be done on the relationship between sleep and behavioral and psychological factors.

Utility

Depending on the method being used, sleep studies can help diagnose or rule out the following disorders: * Sleep-related breathing disorders, such as

sleep apnea Sleep apnea (sleep apnoea or sleep apnœa in British English) is a sleep-related breathing disorder in which repetitive Apnea, pauses in breathing, periods of shallow breathing, or collapse of the upper airway during sleep results in poor vent ...

* Sleep-related seizure disorders * Sleep-related movement disorders, such as periodic limb movement disorder, which is repeated muscle twitching of the feet, legs, or arms during sleep. Sleep studies may be used to diagnose or rule out

restless legs syndrome Restless legs syndrome (RLS), also known as Willis–Ekbom disease (WED), is a neurological disorder, usually chronic, that causes an overwhelming urge to move one's legs. There is often an unpleasant feeling in the legs that improves temporaril ...

(RLS). However, RLS usually is diagnosed based on signs and symptoms, medical history, and a physical exam. * Problems sleeping at night (

insomnia Insomnia, also known as sleeplessness, is a sleep disorder where people have difficulty sleeping. They may have difficulty falling asleep, or staying asleep for as long as desired. Insomnia is typically followed by daytime sleepiness, low ene ...

): caused by stress, depression, hunger, physical discomfort, or other problem. * Sleep disorders that cause extreme daytime tiredness, such as

narcolepsy Narcolepsy is a chronic neurological disorder that impairs the ability to regulate sleep–wake cycles, and specifically impacts REM (rapid eye movement) sleep. The symptoms of narcolepsy include excessive daytime sleepiness (EDS), sleep-r ...

or circadian rhythm sleep disorders. * Problems with nighttime behaviors, such as

sleepwalking Sleepwalking, also known as somnambulism or noctambulism, is a phenomenon of combined sleep and wakefulness. It is classified as a sleep disorder belonging to the parasomnia family. It occurs during the slow wave stage of sleep, in a state of ...

night terror Night terror, also called sleep terror, is a sleep disorder causing feelings of panic or dread and typically occurring during the first hours of stage 3–4 non-rapid eye movement (NREM) sleep and lasting for 1 to 10 minutes. It can last longe ...

s, or bed-wetting * Sleep bruxism (grinding of the teeth during sleep) * Problems sleeping during the day because of working at night or rotating shift work. This sleep problem is called

shift work sleep disorder Shift work sleep disorder (SWSD) is a circadian rhythm sleep disorder characterized by insomnia, excessive Somnolence, sleepiness, or both affecting people whose work hours overlap with the typical sleep period. Insomnia can be the difficulty to ...

. * Sleep studies can also determine problems with stages of sleep. The two primary categories of sleep are non-rapid eye movement (NREM) and

rapid eye movement sleep Rapid eye movement sleep (REM sleep or REMS) is a unique phase of sleep in mammals (including humans) and birds, characterized by random rapid movement of the eyes, accompanied by low muscle tone throughout the body, and the propensity of the s ...

(REM). Normally, four to five series of NREM and REM make up a night's sleep. A change in this cycle may make it hard to sleep soundly.

Types

The most common sleep studies are:

Polysomnogram

Polysomnography records several body functions during sleep, including brain activity, eye movement, oxygen and carbon dioxide blood levels, heart rate and rhythm, breathing rate and rhythm, the flow of air through the mouth and nose, snoring, body muscle movements, and chest and belly movement. These tests are typically done at night in a hospital or sleep center. Polysomnogram tests can give insight into what issue is occurring.

Multiple sleep latency test (MSLT)

The MSLT measures, by several nap opportunities in one day, how long it takes a person to fall asleep. It also determines whether REM sleep appears upon falling asleep. It is usually performed immediately after an overnight study. This test is the standard to test for narcolepsy and idiopathic hypersomnia.

Maintenance of wakefulness test (MWT)

This test measures whether a person can stay awake during a time when she or he is normally awake. Like the MSLT, the MWT is performed in a sleep diagnostic center over 4 - 5 nap periods. A mean sleep onset latency of less than 10 minutes is suggestive of excessive daytime sleepiness.

Home sleep test (HST)

These typically include the individual whose sleep is being studied receiving a portable monitor and may include other items such as a finger clip and an airflow sensor. Items measured include

oxygen saturation Oxygen saturation (symbol SO2) is a relative measure of the concentration of oxygen that is Dissolution (chemistry), dissolved or carried in a given medium as a proportion of the maximal concentration that can be dissolved in that medium at the g ...

, heart rate, airflow, body movement, time spent snoring, sleep position, and brain waves. A home sleep apnea test (HSAT) allows calculation of apnea-hypopnea index and

respiratory disturbance index The respiratory disturbance index (RDI)—or respiratory distress Index—is a formula used in reporting polysomnography (sleep study) findings. Like the apnea-hypopnea index (AHI), it reports on respiratory distress events during sleep, but unli ...

and differentiation between primary snoring and

obstructive sleep apnea Obstructive sleep apnea (OSA) is the most common sleep-related breathing disorder and is characterized by recurrent episodes of complete or partial airway obstruction, obstruction of the respiratory tract#Upper respiratory tract, upper airway lea ...

Sleep questionnaires

* '' Tayside children's sleep questionnaire'': A ten-item questionnaire for sleep disorders in children aged between one and five years old. * '' Children's Sleep Habits Questionnaire''. * ''Cleveland Adolescent Sleepiness Questionnaire (CASQ)'': There are 16 items to measure extreme sleepiness during the day in adolescents aged 11–17 years old.

Sleep study in psychology

Sleep studies have been imperative for the empirical research of sleep psychology. The area of sleep psychology evaluates the physiological, and behavioral factors of normal sleep and sleep disorders along with the neuroscience and brain-wave activity associated with sleep, as well as the study of

circadian rhythm A circadian rhythm (), or circadian cycle, is a natural oscillation that repeats roughly every 24 hours. Circadian rhythms can refer to any process that originates within an organism (i.e., Endogeny (biology), endogenous) and responds to the env ...

Administers of sleep studies

Sleep Specialists are doctors that are board certified in sleep medicine. Doctors qualified to order a sleep study include: *

Primary care physician A primary care physician (PCP) is a physician who provides both the first contact for a person with an undiagnosed health concern as well as continuing care of varied medical conditions, not limited by cause, organ system, or diagnosis. The term ...

: A doctor who provides first contact for a person with a health concern. * Sleep specialists: Board-certified sleep medicine doctors have undergone special training and testing to ensure they can diagnose all sleep-related disorders, including sleep apnea. *

Neurologist Neurology (from , "string, nerve" and the suffix -logia, "study of") is the branch of medicine dealing with the diagnosis and treatment of all categories of conditions and disease involving the nervous system, which comprises the brain, the ...

: The neurologist treats disorders that affect the brain, spinal cord, and nerves. *

Psychiatrist A psychiatrist is a physician who specializes in psychiatry. Psychiatrists are physicians who evaluate patients to determine whether their symptoms are the result of a physical illness, a combination of physical and mental ailments or strictly ...

s: A medical practitioner specializing in the diagnosis and treatment of mental illness.
Medical Definition of Psychiatrist" *

Pulmonologist Pulmonology (, , from Latin ''pulmō, -ōnis'' "lung" and the Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language fam ...

s: A medical practitioner specializing in the diagnosis and treatment of lung and breathing disorders.

References

External links

Sleep Studies
on

National Sleep Foundation The National Sleep Foundation (NSF) is an United States of America, American non-profit, charitable organization. Founded in 1990, its stated goal is to provide expert information on health-related issues concerning sleep. It is largely funded by ...

website
E/M Coding and the Documentation Guidelines: Putting It All Together
on AAFP website {{Sleep Sleep