Fitness and sleep trackers entered the market in 2010 and have exploded in sales over the last 5-6 years. Nearly 33 million of these devices have been purchased in the United States alone as of the end of 2015.1 Worldwide, it was estimated that approximately 8.5 million units were sold in the U.S. in 2015, leading the global market, followed by estimated sales in Western Europe and the Asia-Pacific region of 7.1 and 4.9 million units in 2015, respectively.2 It is predicted that 60 million fitness trackers will be in use globally by 2018.3
With an estimated 50-70 million U.S. adults having a sleep or wakefulness disorder,4 it is little wonder that sleep trackers and other consumer-driven sleep technologies have gained a significant marketing presence. These devices have a fascinating range of purported applications, from tracking sleep duration and quality, to self-guided sleep assessment and education, to entertainment and health-driven social interaction. To this end, sleep technologies take on a sometimes dizzying variety of forms.
Sleep specialists and other healthcare professionals are increasingly exposed to these unregulated sleep technologies via their patients, families, or friends, and may be asked to try to interpret the data from these devices. In this article, we will review some of the more popular or illustrative technologies. We will categorize them into four main spheres: mobile apps and other software, wearables, mattress-embedded devices, and nightstand devices. This article is not meant to be a comprehensive review of all available sleep technologies, but aims to encourage reflection and discussion on current popular and emerging consumer-driven sleep technologies.
Mobile Apps and Software
Mobile applications, or “apps,” and similar software which run on computer-based operating systems such as Android OS, Apple iOS, or Microsoft Windows, can be run on smartphones, tablets, or other electronic devices. Many are free; features-enriched versions generally cost no more than a few dollars. Some apps are simple sleep logs, or noise generators with white noise, nature sounds, hypnosis recordings, or other vocal tracks or light displays which claim to aid in sleep induction. Apps such as Sleep Cycle (Android OS, iOS)5, SleepBot (Android OS, iOS)6, Sleep As Android (Android OS)7 claim to work as sleep trackers, assessing sleep quality and duration. The apps often require the mobile device to be placed on the bed mattress next to the user, and use accelerometer technology available on many smart mobile devices to monitor sleep. Using proprietary algorithms, many of these apps claim to differentiate deep from light sleep, and employ a “smart alarm” that try to wake sleepers during a period of light sleep rather than deep sleep, ostensibly avoiding excessive grogginess upon awakening. Another novel feature employs task-based alarm systems, requiring the user to complete arithmetic or motor-based tasks, or forcing the user to get out of bed, walk, and scan a QR barcode located in another part of the physical environment, thereby guaranteeing a certain degree of wakefulness before the alarm will shut off. An app called GO! to Sleep (iOS)8, developed by the Cleveland Clinic Sleep Disorders Center, uses a standard questionnaire for sleep hygiene, self-reported sleep duration, and other factors to derive a sleep score, and offers daily sleep tips and trivia. SnoreLab (iOS)9 records snoring intensity; it also provides advice to improve snoring and allows users to track efficacy of these therapies by trending their “Snore Scores.” Expanding into Internet-based resources, online interactive websites such as Sleepio10 and SHUTi11 provide customizable cognitive behavioral therapy for insomnia via multimedia modules for a time-based fee. Free software such as SleepyHead,12 available on most major desktop operating systems, provides access to CPAP usage data for end-users.
It is predicted that 60 million fitness trackers will be in use globally by 2018.3
One of the trendier spheres of consumer-driven sleep technologies, wearables include sleep tracker bracelets, necklaces, smart watches, or other technologies which can be attached directly to users or to their clothing. These bear similarities to conventional actigraphy, and often use three-dimensional accelerometer technology to track exercise as well as sleep. Certain devices even employ heart rate, perspiration, and temperature sensors to aid in sleep monitoring. Popular examples of wearables include Fitbit,13 Jawbone,14 Android Wear watches,15 and Microsoft Band.16 Apple Watch17 also supports several apps to track sleep; however, the high battery consumption rate of the Apple Watch typically necessitates nightly recharging, which may limit its use as a sleep tracker. Other examples of wearables include baby clothing with built-in sensors to monitor sleep quality, position, and temperature for infants; and hats and other clothing accessories that claim to track and improve sleep.
Sleep mattresses such as Sleep Number’s IT,18 Kingsdown Sleep Smart Intuitive,19 and Molten Corp’s Leios mattress,20 as well as mattress covers like Luna’s Eight,21 use embedded sensors to measure sleep activity, heart rate, breathing rate, temperature, and even ambient humidity, light, and noise. These technologies often communicate with an accompanying mobile device app to report sleep quality and duration, and offer sleep advice. Some of these devices may even automatically adjust mattress firmness, temperature, and elevation of the head or foot of the bed to optimize comfort.
These technologies are exciting glimpses into potential future tools for sleep evaluation and sleep health, and even in their novelty and entertainment value can entice the average consumer to think more about their sleep…
Several sleep and bedroom sensor standalone monitors can be placed on the nightstand, but often pair with mobile devices placed on the mattress to track sleep and other environmental factors. Smart bulb technology such as the Philips Wake-Up Light22 can be programmed to turn on at a certain time and gradually increase in light intensity over 30 minutes, simulating sunrise and aiming to wake the user gently. Users can also program the color and intensity of smart light bulbs to minimize blue wavelength exposure near bedtime, which may helpenforce a normal circadian rhythm.
As a general rule of thumb, very few of these consumer sleep technologies are medically validated, and even fewer have been robustly tested. For many of these technologies, the algorithms used to derive sleep quality and duration are proprietary. Until further research is done, data from these devices cannot be reliably interpreted and requests for medical interpretation must be approached with caution. When encountering these technologies, one must question how data is collected, what artifact may be introduced (for instance, for mattress-derived sensors, the degree to which sensor artifact from sleep partners, pets, and different mattress textures may affect results), and the level of quality of sleep education and information that is offered by the device or that may be shared through social media or other potentially unvalidated sources. In addition, one must consider how these media-rich devices may be negatively impacting sleep through noise and light pollution. However, these technologies are exciting glimpses into potential future tools for sleep evaluation and sleep health, and even in their novelty and entertainment value can entice the average consumer to think more about their sleep – and ultimately fall to sleep, and in love, with healthy sleep practices.