Sleep apnea is a common medical disorder that is estimated to affect more than 18 million American adults and is linked to attention deficit/hyperactivity disorder, high blood pressure, diabetes, heart attack, stroke, and increased motor vehicle accidents. Diagnosing sleep apnea in the clinic requires the polysomnography test, which is an expensive, time-consuming and labor-intensive process. While portable recording systems are being developed for use in home settings, they require instrumenting either the patient and can result in high failure rates due to detachment of sensors during sleep.

ApneaApp is a contactless solution for detecting sleep apnea events by monitoring the minute chest and abdomen movements caused by breathing on smartphones. Our system works with the phone away from the subject and can simultaneously identify and track the fine-grained breathing movements from multiple subjects. We do this by transforming the phone into an active sonar system that emits frequency-modulated sound signals and listens to their reflections. We have developed algorithms that identify various sleep apnea events including obstructive apnea, central apnea, and hypopnea from the sonar reflections.