New technology to assess sleep apnea: wearables, smartphones, and accessories

Abstract

Sleep medicine has been an expanding discipline during the last few decades. The prevalence of sleep disorders is increasing, and sleep centers are expanding in hospitals and in the private care environment to meet the demands. Sleep medicine has evidence-based guidelines for the diagnosis and treatment of sleep disorders. However, the number of sleep centers and caregivers in this area is not sufficient. Many new methods for recording sleep and diagnosing sleep disorders have been developed. Many sleep disorders are chronic conditions and require continuous treatment and monitoring of therapy success. Cost-efficient technologies for the initial diagnosis and for follow-up monitoring of treatment are important. It is precisely here that telemedicine technologies can meet the demands of diagnosis and therapy follow-up studies. Wireless recording of sleep and related biosignals allows diagnostic tools and therapy follow-up to be widely and remotely available. Moreover, sleep research requires new technologies to investigate underlying mechanisms in the regulation of sleep in order to better understand the pathophysiology of sleep disorders. Home recording and non-obtrusive recording over extended periods of time with telemedicine methods support this research. Telemedicine allows recording with little subject interference under normal and experimental life conditions.

Keywords: Sleep apnea; polysomnography; sleeping disorder.

Figure 1.. Polysomnography system with telemedicine options.

The image shows a system configurable for sleep medicine diagnosis. This particular system can be used for attended polysomnography in a sleep laboratory with all signals to be recorded. Data are stored on a flash memory or are transmitted using a wireless network (or a wired network if required). The system can be set up as attended polysomnography, as home polysomnography, or as home sleep apnea monitoring, depending on the number of sensors and the configuration chosen.

Figure 2.. Non-obtrusive contact-free sleep recording with validated tools.

Two systems for the contactless detection of respiration, body movements, and heartbeat are installed next to the bed of the sleeping subject . Both systems use Doppler technology with radar frequencies to detect the very small movements created by respiration and the heartbeat through a blanket. Larger movements are recorded as well and are taken as major body movements. A third and more traditional technology is tested in parallel. This is actigraphy with a wristwatch-like system. Actigraphy has been accepted as a non-invasive system to quantify sleep-wake times with acceptable accuracy, if being validated.

Figure 3.. Smartphone applications to track sleep without external sensors.

Smartphone applications use movement patterns in order to detect sleep, sleep disorders, and sometimes even sleep apnea . Here, we present the screenshots of a simple app which tracks sleep depth and, based on this, derives sleep duration and a kind of sleep quality. Frame ( a) shows how the smartphone should be used (placed underneath the blanket). Frame ( b) shows the report of a single night with a trace reflecting activity and estimating sleep depth. Frame ( c) shows the sequence of several nights summarized and with that a tracking of sleep quality over one week or a longer time period. Unfortunately, most sleep apps similar to this one have not been checked against a sleep recording or validated clinically and scientifically. They remain to be gimmicks for lifestyle use.