A polysomnogram is a comprehensive test to evaluate patients for possible sleep disorders. This test monitors various physiological processes during sleep to diagnose or rule out specific sleep disturbances. Polysomnograms are typically performed at a sleep center, but may sometimes be self-administered at home using a portable device.
There are two states of sleep. One is rapid eye movement, or REM, sleep, the phase during which dreaming takes place. During REM sleep only the breathing and eye muscles move. The other state of sleep is non-rapid eye movement, or NREM sleep, which has four separate stages differentiated by changing electrical activity in the brain. Normally sleepers alternate between REM and NREM sleep at approximately 90 minute intervals. Polysomnograms monitor patients during both states of sleep.
Reasons for a Polysomnogram
Polysomnograms are administered for a variety of reasons. Patients may be snoring, having trouble keeping awake during the day, or experiencing night disturbances (parasomnias), such as nightmares, bedwetting, or abnormal movements during sleep. Conditions successfully diagnosed through the use of a polysomnogram include:
- Obstructive sleep apnea
- Restless sleep
- REM abnormalities
While extremely helpful in diagnosing most sleep problems, polysomnograms are not able to detect circadian sleep-cycle disorders.
The Polysomnogram Procedure
The patient normally arrives at the sleep clinic 2 hours before bedtime and is put to sleep in a comfortable bed in a room similar to a hotel room. It is important that the patient not take any sleep medication or alcohol before the procedure. Sensors are attached to various parts of the patient's head. These sensors will record a great deal of physiological information as the patient sleeps. Usually the patient's sleep patterns will also be recorded with video devices so that any abnormalities can be observed and evaluated. During the polysomnogram procedure, monitors record the following:
- Blood oxygen levels
- Body position
- Brain waves (EEG)
- Electrical activity of muscles
- Eye movement
- Heart rate
When patients are troubled by sleep disturbances that affect their daily life and health, a consultation with a sleep specialist is in order. The administration of a polysomnogram can help to diagnose the problem. With an accurate diagnosis, the sleep specialist will be able to recommend an appropriate treatment plan to re-establish the healthy sleep patterns necessary to maintain physical well-being, cognitive focus and emotional stability.