Sleep study

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.

Utility
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
 * 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
 * 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.
 * Conditions such as periodic limb movement disorder, which is repeated muscle twitching of the feet, arms, or legs 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.
 * Sleep studies can also determine problems with stages of sleep. The two stages 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.

Types
The most common sleep studies are:

Simple sleep study
It is a simple sleep study done within the home premises.

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.

Multiple sleep latency test (MSLT)
The MSLT measures, several times in one day, how long it takes the patient to fall asleep. It also determines whether REM sleep appears upon falling asleep.

Maintenance of wakefulness test (MWT)
This test measures whether you can stay awake during a time when you are normally awake.

External Sources

 * Sleep Studies on National Sleep Foundation website