AHI - Left Side Test

This measure represents the apnea hypopnea index during left side sleeping, counting the number of apneas and hypopneas per hour that are associated with at least a 3 percent drop in blood oxygen levels. Oxygen desaturation reflects reduced airflow through the upper airway during sleep.

Left side sleeping often improves airway patency compared with back sleeping and is sometimes favored for additional cardiovascular or reflux related benefits. A low left side AHI relative to supine AHI suggests positional obstructive sleep apnea and indicates that side sleeping may substantially reduce breathing disturbances and overnight hypoxia.

That said, left side AHI does not capture non desaturating events that still cause sleep fragmentation, and it may appear artificially low if the person spends little time in this position during the study. Positional data should always be interpreted alongside total AHI, symptoms, and oxygen metrics such as time spent below normal oxygen levels.