The preparations for polysomnographic recording sessions typically proceed like this.

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Sleep Lab Studies

Let's look at the steps of a polysomnogram in the form of an overnight sleep study. The patient arrives in the evening, armed with items such as pajamas, toothbrush, book, pillow and morning attire. The sleep lab workers escort him to a private room where he can put his PJs on and get settled in for the night.

Next, a lab technician will hook up an assortment of electrodes to the patient's skin and scalp, along with two belts to encircle his chest and waist. These are to measure how much effort he exerts to breathe while sleeping, and another attachment called an oximeter measures how much oxygen is in his blood.

The electrodes, however, are the most important components -- they record all sorts of activity throughout the evening. Different ones are dedicated to conducting different tests: The electroencephalogram (EEG) measures brainwaves, the electromyogram (EMG) measures muscle activity, the electrooculogram (EOG) measures eye movements, and the electrocardiogram (EKG) measures heart activity. The sleep lab technologists will also hook up a sensor to measure airflow through the nose and mouth, and set up a microphone to record snores and a video camera to get a visual record of body movement.

Patients are allowed to spend some time relaxing, perhaps reading or watching TV, and then they're supposed to fall asleep when ready. It might seem odd, but according to sleep labs, most patients don't have much trouble going to sleep -- or at least, much trouble in regard to the electrodes and other strange apparatus involved in the process. Then throughout the evening, all the results will pour in to the monitoring station. Once the results are in, a sleep lab specialist will interpret the results to try to determine a diagnosis and decide on an appropriate form of treatment.

On the next page, we'll look at some of the common treatments someone might receive from a sleep lab.