Polysomnograms are a type of diagnostic sleep study. Doctors may request that a patient take one to determine what is going on during an overnight sleep. The tests are done in a sleep laboratory. There are now hundreds of these sleep labs around the country.
Patients are advised to avoid naps, caffeine and alcohol on the day of their polysomnogram.
Once in the sleeping room, monitoring devices are applied to the body to collect information. Sensors monitor your brainwaves (EEG activity), heart rate (EKG), eye movements, leg muscle activity, and chest and stomach movement. Air flow from your nose and mouth are recorded. A sensor that clips onto a finger monitors the amount of oxygen in the blood.
If your doctor has specific questions, other monitors might be applied, for instance to measure eye and jaw muscle movement or leg muscle movement. Information is gathered from all leads and fed into a computer and outputted as a series of waveform tracings which enable the technician to visualize the various waveforms, assign a score for the test, and assist in the diagnostic process.
Usually a polysomnogram ends around 6 AM and the patients can return to their usual daytime routine.
If you get a polysomnogram from a sleep clinic, demand the results. You should get a copy in addition to the results they send to the doctor. Don't let them talk you out of getting a copy.
Polysomnograms are widely used in diagnosis of sleep disorders and are indeed the main procedure at a typical sleep clinic. The interpretation is somewhat subjective, as so much in medical diagnosis is. The polysomnogram can tell how lomg it took for the person to get to sleep and the total time of nighttime awakenings. While many practitioners use a nighttime wake time of 30 minutes or more as a cutoff for the line between normal sleepers and insomniacs, there are suggestions that this criteria misses some people who should be identified as having insomnia.