According to the AASM, the polysomnography (PSG) test is the gold standard test for quantifying and qualifying sleep disorders. PSGs usually happen overnight in a Centre for Respiratory Sleep Physiology to ensure careful monitoring of the parameters recorded. Depending on the condition of the person, the PSG can also be done during the day or even at your home. Here is a breakdown of a PSG:sleep_b2.jpg

The recording of brain activity from electrodes attached to the scalp.

The recording of the activity in the muscles from electrodes attached to the chin, legs or arms.

The recording of the activity in the heart from electrodes attached near the heart.

The recording of the movement of the eyes from electrodes attached near the eyes.

Nasal and oral airflow: The recording of ventilation from a nasal cannula secured just under the nose.

Respiratory effort (chest and abdominal muscles): The recording of the activities of the respiratory muscles from one band around the chest and another around the abdomen.

Snoring: The recording of the sound of airflow in the soft tissues of the palate or uvula from a microphone at neck level.

Oxygen saturation: The recording of the amount of oxygen in the blood through a probe on the fingertip. Other data can also be recorded, in order to explore sleep-related movement disorders (leg movements, jaw clenching) or blood pressure. An infrared light may also be added to check for parasomnias (sleepwalking, nightmares, RBD, etc.) during sleep.

Most people have no trouble “sleeping” in a
One polysomnography is usually sufficient to establish a diagnosis. A PSG is essential to determine the presence of more than one sleep disorder and thus, make an accurate differential and positive diagnosis of the suspected condition.


American Academy of Sleep Medicine. International Classification of Sleep Disorders: Diagnostic and Coding Manual. 2nd ed. Rochester, 2005.

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