Sleep studies are tests that watch what happens to your body during sleep. The studies are done to find out what is causing your sleep problems. Sleep problems include:
- Sleep apnea, when an adult regularly stops breathing during sleep for 10 seconds or longer. This may be caused by blocked airflow during sleep, such as from narrowed airways. Or it may be caused by a problem with how the brain signals the breathing muscles to work.
- Problems staying awake, such as narcolepsy.
- Problems with nighttime behaviors, such as sleepwalking, night terrors, snoring.
- Conditions such as periodic limb movement disorder, which is repeated muscle twitching of the legs or arms during sleep. Sleep studies can also determine whether you have a problem with your stages of sleep. The two stages of sleep are non-rapid eye movement (NREM) and rapid eye movement (REM). Normally, NREM and REM alternate 4 to 5 times during a night’s sleep. A change in this cycle may make it hard for you to sleep soundly.
The most common sleep studies are:
- Polysomnogram. This test 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 your mouth and nose, snoring, body muscle movements, and chest and belly movement.
- CPAP Titration Polysomnogram. This test records the same body functions as listed above but records how they change when different pressures are used with the continuous positive airway pressure (CPAP) machine used as a common treatment of sleep apnea.
- Multiple sleep latency test (MSLT). This daytime test measures how long it takes you to fall asleep when you attempt to nap.It is a measure of how sleepy you are. It also determines how quickly you enter REM sleep. ( A quick entry into REM sleep may be diagnostic of narcolepsy).
- Maintenance of wakefulness test (MWT). This daytime test measures whether you can stay awake and alert during a time when you are normally awake. Results may be used to show if your sleepiness is a safety concern to you or the public or to check your response to treatment.
Polysomnograms are usually performed in a sleep lab. Occasionally, a home test may be ordered for certain conditions.