A sleep study is a test that records the activity of the body during sleep. 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, 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 disorders. 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.
Depending on the method being used, sleep studies can help diagnose or rule out the following disorders:
The most common sleep studies are:
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. [2] These tests are typically done at night in a hospital or sleep center. Polysomnogram tests can give insight into what issue is occurring. [3]
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. [2] [4] It is usually performed immediately after an overnight study. This test is the standard to test for narcolepsy and idiopathic hypersomnia. [5]
This test measures whether a person can stay awake during a time when she or he is normally awake. [2] [4] 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.
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, heart rate, airflow, body movement, time spent snoring, sleep position, and brain waves. [6]
A home sleep apnea test (HSAT) allows calculation of apnea-hypopnea index and respiratory disturbance index and differentiation between primary snoring and obstructive sleep apnea. [7]
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 rhythms. [13]
Sleep Specialists are doctors that are board certified in sleep medicine. Doctors qualified to order a sleep study include: