Methodologies and Wearable Devices to Monitor Biophysical Parameters Related to Sleep Dysfunctions: An Overview

Abstract

Sleep is crucial for human health from metabolic, mental, emotional, and social points of view; obtaining good sleep in terms of quality and duration is fundamental for maintaining a good life quality. Over the years, several systems have been proposed in the scientific literature and on the market to derive metrics used to quantify sleep quality as well as detect sleep disturbances and disorders. In this field, wearable systems have an important role in the discreet, accurate, and long-term detection of biophysical markers useful to determine sleep quality. This paper presents the current state-of-the-art wearable systems and software tools for sleep staging and detecting sleep disorders and dysfunctions. At first, the paper discusses sleep’s functions and the importance of monitoring sleep to detect eventual sleep disturbance and disorders. Afterward, an overview of prototype and commercial headband-like wearable devices to monitor sleep is presented, both reported in the scientific literature and on the market, allowing unobtrusive and accurate detection of sleep quality markers. Furthermore, a survey of scientific works related the effect of the COVID-19 pandemic on sleep functions, attributable to both infection and lifestyle changes. In addition, a survey of algorithms for sleep staging and detecting sleep disorders is introduced based on an analysis of single or multiple biosignals (EEG—electroencephalography, ECG—electrocardiography, EMG—electromyography, EOG—electrooculography, etc.). Lastly, comparative analyses and insights are provided to determine the future trends related to sleep monitoring systems.

Brain Waste Removal System and Sleep: Photobiomodulation as an Innovative Strategy for Night Therapy of Brain Diseases

“…Recent surveys of consumer sleep technologies demonstrate some demand for optional physical interventions during the sleep process aimed to improve the quality of sleep [ 140 ], although the requirement of strong scientific evidence to legitimize claims about utility, safety, and efficacy, as well as for informed choice and public trust, are emphasized [ 141 , 142 ]. Sleep technologies are presented on the market as various sleep-tracking devices [ 143 , 144 ] ( Figure 3 a–d).…”

“…Commercial sleep-tracking technologies include radars; near-infrared and thermal imaging devices; bedding-based sleep sensors; and wearable body sensors designed to be fixed on wrist, finger, feet, waist, chest or head [ 143 , 145 ]. Headbands are also capable of performing electroencephalography (EEG) recording and analysis that sufficiently improve sleep detection [ 142 , 144 ].…”

“… Sleep-tracking gadgets: ( a ) BrainBit headband [ 143 ]; ( b ) Philips Smart Sleep Deep Sleep Headband [ 142 ]; ( c ) Oura ring smart sleep tracker [ 144 ]; ( d ) sleep tracker 2 mm thick belt to be placed under the sheet on a bed [ 144 ]. …”

Recent Progress in Long-Term Sleep Monitoring Technology

“…These stages alternate throughout the night, a phenomenon known as the sleep cycle. A cycle is roughly 2–3 h ( Figure 3 ) [ 41 ]. Sleep with several complete sleep cycles is healthy.…”

“… ( a ) Sleep cycles and REM sleep [ 41 ]. Reproduced under the terms of the CC-BY Creative Commons Attribution License, Copyright 2022 by the authors, published by MDPI.…”