Certified Polysomnographic Technician (CPSGT) Practice Exam 2025 - Free CPSGT Practice Questions and Study Guide.

The hypnogram serves as a visual representation of the different stages of sleep and periods of wakefulness throughout a sleep study. By plotting the various sleep stages, such as REM and non-REM sleep, over the course of the night, the hypnogram provides valuable insights into an individual's sleep architecture. This graphical depiction helps clinicians assess the quality of sleep, identify sleep disorders, and evaluate sleep patterns. The understanding of these stages is crucial in diagnosing conditions like sleep apnea, insomnia, or narcolepsy, making the hypnogram an essential tool in polysomnography.

In contrast, the other options address different functions that are not the primary role of a hypnogram. For instance, measuring oxygen levels pertains more to pulse oximetry data or other monitoring systems rather than the hypnogram itself. Similarly, heart rate variability is recorded through ECG or other cardiac monitoring techniques, and audio recordings of sleep sounds are not part of the hypnogram's function, which focuses solely on the visual representation of sleep stages.