How is hypopnea defined in polysomnography?

Hypopnea in polysomnography is defined as a reduction in airflow that leads to a significant decrease in oxygen saturation. This condition is typically characterized by a decrease in respiratory effort or airflow for a certain duration, usually accompanied by a measurable drop in blood oxygen levels. Such reductions can impact sleep quality and are associated with various sleep disorders, particularly obstructive sleep apnea.

Understanding hypopnea is crucial in the context of sleep studies, as it reflects disturbances in breathing during sleep, which can lead to fragmented sleep and increased risk of cardiovascular problems if not addressed. In contrast, the other options do not adequately capture the definition or implications of hypopnea within the scope of polysomnography.