Polysomnogram (PSG)

What is a polysomnogram?

A polysomnogram is a procedure that measures important bodily functions during sleep. Many sensors are used to make these measurements. None of the sensors cause significant discomfort. The bodily functions that are measured are:

Sleep - Electrodes stuck to the scalp, ear, chin and legs tell us when you're asleep and whether you're in REM or NREM sleep (see glossary for definitions of REM and NREM.)

Breathing - A sensor is placed below your nose that measures airflow; elastic bands are placed around your chest and abdomen to sense when you're making breathing efforts.

Oxygen level - A finger clip measures the amount of oxygen in your blood.

Snoring - A small microphone records snoring sounds.

Movements - A videocamera that can record images in the dark (using infrared technology) records your movements while in bed.

Heart rate and rhythm - Electrodes on your chest record your heartbeat (EKG). Typically you come to the sleep lab several hours before bedtime.

How can I sleep with all these things on me?

First of all, remember that none of the monitoring devices cause significant discomfort. Although we don't expect people to sleep quite as well in the lab as at home, most people sleep surprisingly well. Certainly most people sleep well enough for the study to be very useful. You are free to sleep in any position you wish and may use the bathroom whenever you need. A sleep technologist is present in the adjoining control room at all times and is available to answer questions or try to make you comfortable. Each sleeping room has a television, bedside table, closet and reading light. Preparation for the study is very simple; written instructions are provided to you before you have the study.