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Sleep Studies

Sleep studies are tests that monitors what happens to your body during sleep either at night time or during the day. The studies are done to find out what is causing your sleep problems. They are involved in placing multiple electrodes over your head, around eyes, around ears and around your heart to detect you EEG pattern, EKG pattern and EMG activities.  There are many senses placed on varies of your body parts to detect your breathing, chest and abdominal movement. There are video camera and audio devise to observe your activities during the sleep. The sleep study your doctor ordered is usually overnight sleep study including diagnostic study and CPAP titration.  Most sleep study is two-nights.   One  split sleep study is sometimes conducted (first 2-3 hours is diagnostic and remaining night is CPAP titration).  However, it dose not gather adequate data.

If you have following problem, sleep study may need to be done, at least to see a doctor to talk aboutsSleep problems.

  • Snore, restless sleep and daytime fatigue or sleepiness.  These indicate that you are suffering a condition of obstructive sleep breathing.  This condition is easily treatable and the treatment is one hundred effective.  The result is day and night difference.
  • Abnormal behaviors during the sleep, such as sleepwalking, night terrors, or bed-wetting or acting out from dream.
  • Persistent insomnia (difficulty to fall asleep and stay asleep). This may be caused by periodic limb movement disorder and, possibly by obstructive sleep breathing.

The most common sleep studies are:

  • Polysomnogram (NPSG). This test records several body functions during sleep, including brain activity, eye movement, oxygen saturation in blood, 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. This is most commonly ordered sleep study.  Diagnostic sleep study or baseline sleep study is conducted to determine if the patient has obstructive sleep apnea, how severe  the obstructive sleep is, how low the oxygen saturation in blood drops or some other sleep related illness, such as PLM, RBD, nocturnal seizure.  CPAP titration sleep study is conducted to determine the CPAP pressure needed to keep o the patient’s upper airway open to minimum resistance.  The optimum pressure is to eliminate all snore, apnea and hypopnea.
  • Multiple sleep latency test (MSLT).  This test measures how long it takes you to fall asleep. This is daytime sleep study.  The patient usually has had overnight sleep study in previous night. And then he/she took 4-5 naps during the day. Each nap lasts anywhere between 20 to 30 minutes. The technician will instruct the patient to try to fall asleep when nap begins.  In between naps, the patient has to keep him/herself occupied to avoid falling asleep.  A drug screen may be done to determine if the patient take drugs. And caffeinated beverages should be avoided before or during the test.  The patient is also instructed to avoid sedative or stimulant medications at least for two weeks.  The physician determines how quick a patient can fall asleep or how many REM onset sleep.  This test is used to determine if patient has narcolepsy or determine severity of daytime sleepiness.  Sometime, it is required to be done for employment for the patient who has been diagnosed with OSA.  Less than 10 minutes sleep onset is considered significant daytime hypersomnolence.  Less than 5 minutes sleep onset is considered pathologic daytime hypersomnolence.  If more than two REM onset sleep is consistent with the diagnoses of narcolepsy.
  • Multiple wake test (MWT). This test measures the ability of the patient to stay awake when in quiet and restful environment.  It is done like MSLT study.  However, the patient is instructed to stay awake instead of trying to fall asleep.  There are no reliable criteria to determine if significant daytime sleepiness still exists.  Lots of entities required this test to be done for employment or licensure.