Overview of Overnight Sleep Study (or Polysomnography or PSG)
The most popular test performed at most sleep centers is polysomnography, or sleep study, during which a patient sleeps overnight in a special room designed to record heart function, breathing, sleepwalking and symptoms of insomnia and sleep deprivation. Using this information, a sleep expert is able to diagnose such sleep disorders as obstructive sleep apnea and move forward with the patient toward an appropriate treatment option. In the special room, several measurements are recorded, including movement of air throughout the lungs while breathing, heart rate, level of oxygen in the blood, position of the sleep person’s body, brain activity, muscle activity, eye movement and difficulty sleeping and staying asleep. A team of special sleep experts will sometimes also stay overnight to observe movement and activity throughout the night, though many centers use video cameras and review the visuals later.
Preparing for a Sleep Study
Caffeine, alcohol and medications to help you sleep should not be consumed before you undergo sleep study. About 2 hours prior to your normal bedtime, a patient will arrive at the sleep center. The room designated for sleep is usually very comfortable, much like a bedroom in a home or a hotel room. Before lying down to sleep, the patient will need to be equipped with monitoring tools, such as having special electrode wires placed on his or her head and face, particularly near the area surrounding the eyelids. Heart and lung monitors will also be attached to the person’s chest to record rate of breathing and heart function. Unfortunately, some patients find it difficult to fall asleep with this equipment installed—although it is completely necessary if a thorough polysomnogram is to be produced the next morning.
Why Staying Overnight for Sleep Study is Important
The stages of sleep can be split into 2 categories: rapid eye movement (REM) sleep and non-rapid eye movement (NREM) sleep. While a person is experiencing REM sleep, he or she will dream vividly, but will not move his or her muscles, except for those in the eyes and those necessary for breathing. NREM sleep, on the other hand, occurs at all other moments of sleep and can be split up further into stages dependent on electrical activity in the brain, monitored by electroencephalogram (EEG). REM and NREM stages of sleep cycle through over the course of one night’s rest, alternating with one another every hour and a half, depending on interruptions in sleep and person-to-person variation. It will be an important aspect of the sleep study to record how long it takes a person to fall asleep, enter REM sleep and cycle through NREM sleep.
During a sleep study, sleep experts can match up recording data collected throughout the night with the stages of sleep (REM or NREM) occurring at the time that symptoms show. For example, during a night terror, a person’s heart would obviously be beating very quickly. Or, a minor case of sleep apnea could be detected if monitored breathing shows results of irregular air flow to and from the lungs. There are special devices that patients may also acquire from a sleep center if a he or she would rather sleep at home. A sleep expert from the sleep center will need to travel to the home prior to the test to set up equipment. Talk to a sleep center to discuss the best sleep study option for you.