Sleep studies are tests that record the body activity during sleep. They are helpful in identification of sleep disorders. Polysomnography, a type of sleep study, is the gold standard to rule out obstructive sleep apnea. If a home study does not find obstructive sleep apnea, but the patient still complains of unrefreshing sleep and daytime sleepiness, an in-lab polysomnogram may be necessary to find other possible disorders.
Sleep studies can help diagnose or rule out:
- Sleep-related breathing disorders, such as sleep apnea
- 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 (RLS). However, RLS usually is diagnosed based on signs and symptoms, medical history, and a physical exam.
- Problems sleeping at night (insomnia) : caused by stress, depression, hunger, physical discomfort, or other problem
- Sleep disorders that cause extreme daytime tiredness, such as narcolepsy or circadian rhythm sleep disorders.
- Problems with nighttime behaviours, such as sleepwalking, night terrors, or bed-wetting
- Bruxism or 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.
- 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 (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.
The most common sleep studies are:
Simple sleep study.
A simple sleep study is done in the home.
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.
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.
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)
The Home Sleep Test also called an Out of Sleep Center Test (OCST) is used exclusively for the diagnosis of sleep apnea. Portable equipment is sent home with the patient. The channels are usually limited to airflow, respiratory effort, and oximetry.
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- "Medicaid and Health Choice and Clinical Coverage Policy No.: 1A-20" (PDF). NC Division of Medical Assistance Sleep Studies Polysomnography Services. Retrieved 27 December 2012.
- "Sleep study and Home Sleep Test". ASA. Retrieved 30 July 2016.