PSGs

PSG is an acronym for polysomnography, a comprehensive sleep study used to diagnose sleep disorders. The plural PSGs refers to multiple polysomnography recordings conducted in individuals or research settings. Polysomnography is a multi-parametric test that records brain activity, eye movements, and muscle tone, together with heart rate and rhythm, respiratory effort and airflow, blood oxygen saturation, and sometimes limb movements, body position, and video monitoring. In-lab PSGs are typically performed overnight with a trained technologist supervising the recording; ambulatory PSGs may be used in some cases but often provide fewer channels and less control over testing conditions.

PSGs play a central role in diagnosing sleep disorders such as obstructive sleep apnea, central sleep apnea, narcolepsy, REM sleep behavior disorder, periodic limb movement disorder, and various parasomnias. Derived metrics include sleep onset latency, total sleep time, sleep efficiency, wake after sleep onset, REM latency, and distribution of sleep stages. Respiratory parameters yield the apnea-hypopnea index, apnea index, hypopnea index, and oxygen desaturation index; limb movement indices quantify periodic limb movements during sleep.

Interpretation of PSG results guides treatment decisions, including continuous positive airway pressure therapy, auto-adjusting PAP, oral appliances, and pharmacological options for specific conditions. Limitations include first-night effects, night-to-night variability, and the artificial sleep environment that may affect sleep architecture. While home PSGs are increasingly used for appropriate indications, in-lab PSGs remain the reference standard for comprehensive diagnostic testing and for evaluating complex sleep disorders.