Dynamics of Snoring Sounds and Its Connection with Obstructive Sleep Apnea

TL;DR

This study investigates the relationship between irregular snoring sounds and obstructive sleep apnea, proposing a new index (STII) and using Hurst analysis to classify apnea severity from snore recordings.

Contribution

It introduces the snore time interval index (STII) as a simple measure correlating with apnea severity and applies Hurst analysis for effective classification of sleep apnea severity levels.

Findings

STII correlates well with apnea-hypopnea index.

Hurst analysis distinguishes between mild and severe apnea.

Irregular snores are indicative of obstructive sleep events.

Abstract

Snoring is extremely common in the general population and when irregular may indicate the presence of obstructive sleep apnea. We analyze the overnight sequence of wave packets --- the snore sound --- recorded during full polysomnography in patients referred to the sleep laboratory due to suspected obstructive sleep apnea. We hypothesize that irregular snore, with duration in the range between 10 and 100 seconds, correlates with respiratory obstructive events. We find that the number of irregular snores --- easily accessible, and quantified by what we call the snore time interval index (STII) --- is in good agreement with the well-known apnea-hypopnea index, which expresses the severity of obstructive sleep apnea and is extracted only from polysomnography. In addition, the Hurst analysis of the snore sound itself, which calculates the fluctuations in the signal as a function of time interval, is used to build a classifier that is able to distinguish between patients with no or mild apnea and patients with moderate or severe apnea.