# Polysomnography **Domain:** Sleep Medicine / Neurophysiology **Doc Type:** Scientific Concept Node **Maturity:** Established **Related:** [[Electroencephalography]], [[Electrooculography]], [[Electromyography]], [[DICOM Working Group 32]] --- ## Definition **Polysomnography (PSG)** is a synchronized sleep study combining multiple physiological signals, commonly EEG, EOG, EMG, airflow, respiratory effort, oxygen saturation, and cardiac measures. ## Continuity relevance PSG demonstrates why neural records are often multimodal event systems rather than isolated channels. Sleep stage, vigilance, physiology, and recording conditions affect how electrical brain activity should be interpreted over time.