Multisensory wearable technology to monitor sleep and circadian rhythms

Richard P Knudsen MD FAASM CNP FAAP

Sleep Disorders

Updated 07.19.2024
Expires For CME 07.19.2027

Multisensory wearable technology to monitor sleep and circadian rhythms

Author: Richard P Knudsen MD FAASM CNP FAAP

See Contributor Disclosures

Editor: Antonio Culebras MD FAAN FAHA FAASM

Multisensory wearable technology to monitor sleep and circadian rhythms

In This Article

Quick Link

Introduction

Overview

There is an increasing awareness of the importance of optimized sleep. To achieve supreme sleep—in quality, quantity, and architecture—many folks are turning to devices to better realize their goal. Certainly, daytime performance hinges on the integrity of nocturnal sleep. In this era of deep learning, algorithms, and “AI,” the sensors developed within the industry have made tremendous gains toward the advancement of sleep monitoring, especially in the setting of at-home sleep assessment.

This article discusses certain types of monitors currently available on the market. The article does not attempt to be complete as the product line is ever evolving. Many are considered “wellness products.”

Many devices strive toward FDA clearance. Newer sensors require validation testing, which is cumbersome but necessary. The traditional polysomnogram is the “gold standard” for accuracy of interpretation of achieved physiological data. Many outfits do not disclose their “black box” proprietary formulas. Transparency is poor, and validation is skewed.

In-ear sensor EEG technology was shown to have significant value as a conventional measure (01).

One particular human malady under study via multisensory monitoring is obstructive sleep apnea. This is a common disorder (most common form of abnormal sleep pattern) and is reaching greater preponderance given “globesity,” or global obesity. Obstructive sleep apnea is considered a significant and independent cardiovascular risk factor; it is underrecognized and undertreated in everyday clinical practice. The pandemic of individuals with unhealthy body mass is a major burden on society. General detection of obstructive sleep apnea in the setting of concurrent obesity is key. This cannot be sufficiently accomplished by way of in-lab polysomnography studies: the volume is simply too great.

The wearables are also valuable in the diagnosis of insomnia and circadian rhythm disorders. The data include time in bed as well as other parameters, including total sleep time, wake after sleep onset, sleep onset latency, and periodic limb movements.

Key points

	• Software (SaMD or Software as Medical Device) is playing an increasingly important and critical role in healthcare with many clinical and administrative purposes. There is a veritable digital health revolution, with the ability to capture different biosignals with the generation of large datasets (Big Data) and the potential of offering unprecedented insight into the user’s health status. The importance of measuring sleep as an integrated component of wellness is understood.
	• Masses of people suffer from significant sleep disorders. These can be detected with reasonable accuracy and efficiency via FDA-cleared wearable multisensory monitors that are now available on a large scale.
	• There are distinct advantages to nonclinical monitoring outside of the in-lab sleep setting. Validation studies are indicated and are typically compared to polysomnography.
	• Many sleep monitoring devices are reviewed in this article. No endorsements are made. They are marketed in many forms, including ring, patch, chin, headband, button, in-ear, and mask, among others.

Discussion

There have been tremendous advances in the arena of portable electronics for sleep monitoring. This article reviews certain varied brands of “gadgets” after providing an overview of the expanding field of home sleep monitoring.

Approximately 12% of the U.S. population suffers from obstructive sleep apnea, which is often undiagnosed and undermanaged. The symptoms are not particularly noticed during sleep. The apnea/hypopnea with deoxygenation creates cortical arousal and sleep disruption. Obstructive sleep apnea is a major economic burden due to loss in productivity and the increased cost of likely comorbidities (such as hypertension, hyperlipemia, and type 2 diabetes mellitus).

Currently, there is a movement toward home sleep testing. Monitoring could focus on the elderly, snorers, obese candidates, brain workers, and those invested in aviation or outdoor sports.

The advantages of home sleep testing (nonclinical setting) over in-lab polysomnography include the following:

	• Compact, less equipment, noninvasive
	• Ambulatory, ease of use, no “first night effect,” per se
	• More representative of personal sleep given the home bedroom environment
	• Less expensive: cost-effective
	• Less personnel consuming, conducive to public health considerations
	• More scale and efficiency in order to meet increasing demand
	• Comfortable, accurate* (+/-), private, convenient
	• Outperforms standard actigraphy
	• Bluetooth compatible, less workload, streamlined management
	*less accurate than on-site lab testing, leading to possible misdiagnosis (limited access to raw data; difficulty with dark skin/tattoos; limited standardization and validation; diminished accuracy if sleep is fragmented or if bed is shared with pet or partner)

The American Academy of Sleep Medicine (AASM) offers a position statement regarding home sleep testing (03):

Consumer sleep technologies (CSTs) cannot be utilized for the diagnosis and/or treatment of sleep disorders at this time. … It is the position of the AASM that CST must be FDA cleared and rigorously tested against current gold standards if it is intended to render a diagnosis and/or treatment. Given the unknown potential of CST to measure sleep or assess for sleep disorders, these tools are not substitutes for medical evaluation. However, CSTs may be utilized to enhance the patient-clinician interaction when presented in the context of an appropriate clinical evaluation.

Meltzer and colleagues state: “Despite its low cost and ease of use for consumers, neither sleep-recording mode of the Fitbit Ultra accelerometer provided clinically comparable results to PSG. Further, pediatric sleep researchers and clinicians should be cautious about substituting these devices for validated actigraphs, with a significant risk of either overestimating or underestimating outcome data including total sleep time and sleep efficiency” (04).

There is limited validation of the currently available technology in wearable devices, which is a primary factor curbing their large-scale use. Commonly, home sleep tests would overestimate total sleep time along with sleep efficiency. For example, “quiet wakefulness” during bouts of insomnia were problematic. Inter-device reliability and non-standardization are at issue as well.

The inter-scorer reliability – with senior scorers of polysomnography – is not well established. Younes and colleagues concluded that manual scoring of nonrapid eye movement sleep stages is highly unreliable among highly trained, experienced technologists (06). This inherently confounds the attempt to use polysomnography interpretation as the gold standard for validation of burgeoning technology when it is quite imperfect. Incidentally, the AASM offers a sleep facility interscorer reliability requirement in which there must be 12 polysomnography tests per year, compared by epoch.

The most commonly used at-home test (equipment type) for sleep apnea is type 3. By contrast, the formal in-lab study is deemed type 1 – the “gold standard.” The type 3 test tracks the following, by definition: breathing effort and rate, airflow, snoring, and blood oxygen saturation.

Body position, heart rate and variability, nasal pressure, and apnea hypopnea index are also understood, along with sleep onset, total sleep time, sleep efficiency, and wake after sleep onset.

Type 1 testing equipment includes that of type 3 as well as heart rate/heart rate variability, rhythm, and sleep stages, along with carbon dioxide output.

Recent wearable sensors with portable electronics include sleep stages. This is a key component in the field of sleep medicine. The sleep relevant metrics related to EEG include sleep stages: W, NREM, REM or wake, non-REM (stages I, II, and III) and REM. Sleep cycling and continuity, beyond sleep architecture, are important parameters.

A valuable screening tool toward the detection of obstructive sleep apnea is the STOP-BANG questionnaire.

S	Snoring
T	Tired
O	Observed apnea
P	high blood Pressure
B	Body mass index > 35
A	Age 50 and older
N	Neck circumference wider than 16 inches
G	Gender (men are at higher risk of obstructive sleep apnea)

The latest wearable devices rely not only on 3D accelerometers but also on reflective photoplethysmography. Optical photoplethysmography sensors allow an optimal measure of the changes in blood pressure and blood volume at the periphery. Of note, when undertaking a home sleep test, remember no hand cream, fingernail polish, jewelry, nor tattoo marks. Wear snugly for improved signal-to-noise ratio.

Finally, wearable sleep monitoring devices to detect obstructive sleep apnea in the setting of “globesity” is aimed at remediation. Pharmacotherapy to curb cravings may prevent obesity and, thus, obstructive sleep apnea and downstream pathologies (eg, stroke, heart attack, migraine, dementia, T2DM, lipemia, hypertension, mood disorders, accidents). Short of discipline and nutrition/dietetics and exercise, GLP-1 receptor agonists and SGLT-2 inhibitors may play a major role (05).

As the field gains in sophistication, the Department of Defense will express interest as most soldiers are sleep restricted. In vulnerable adults, this sleep loss impacts performance on the next day. One measure of disrupted sleep continuity is the accumulation of cortical microarousals. Microarousals are brief (less than 15 seconds) shifts in EEG power (usually theta ranges) and correlate with altered daytime functioning and negative health outcomes across a sleep period (02).

Regarding various modalities, as marketed, this article will focus on an array of products, including headband, ring, armband, patch, topic phonic device, wristband, and mask.

Dreem Headband

FDA cleared. First dry EEG data collection device, AI-assisted. From Beacon Biosignals.
Belun Ring

FDA cleared. Medically accurate, including sleep stages. Sequential nightly reports ->> "treatment tracking." Detects ANS response.
Oura Ring

Multisensor detector, needs validation. “Clone” – UltraHuman Air ring. Lightweight: 2.4 gm. Quality metrics, abundant data, adenosine clearance window, temperature detection for ovulatory or personalized menstrual cycle, and co...
Somno-Art

Electronic armband. Medical grade sleep reports with robust and precise data acquisitions, including sleep architecture. Purposed for academic and research or pharmacologic investigations and development.
Neuroon

Wearable eye mask. "Proprietary” algo. Dedicated meditation device. Visual, auditory, and vibratory stimuli customized during REM sleep for lucid dreaming. Coordinates with smart bedroom (lighting, temperature, transitioning).<...
Wesper

Level III HSAT signals. Wireless patch, streamlined, quality signals. Cutting edge biometric data analysis. Monthly program toward management of sleep. Ongoing care and titration using a cloud-based system. Wealth of informatio...
AcuPebble SA100

Sophisticated signal processing based on recorded sounds. Attached to the base of the neck to record sounds related to respiration and cardiac status. Comfortable and noninvasive. Clinically validated.
FitBit

Apple watch-type products are considered accurate, convenient, attractive, and "just a glance away." Health and fitness tracking. Emergency SOS alert, music, directions, cellular available, swimproof (water-resistant), arrhythm...
REM-enhancing experience

"What would you do if you could consciously recognize and control your dreams?” Lucid dreaming--"improve sleep and improve lives." Better moods, increased creativity, reduced stress, and enhanced problem-solving skills. Afforda...

The Dreem headband monitors both sleep-related physiological signals and accurately processes them into sleep stages. The study sample was small and homogeneous, with the need for a more diverse population.

The FitBit and Jawbone UP3 are defunct without a companion app. Consumers were disgruntled over the extinction.

A non-exhaustive list of home sleep testing services includes the following: MedBridge Healthcare, ApneaMed, betternight, SleepViewDIRECT, Gem Sleep, General Sleep, Ognomy, Onera, dreamclear, SleepCareonline, the SLEEP DOCTOR, snap diagnostics, Virtuox, ZOLL Itamar, Z Machine, NightOwl, WatchPat-One, and iButton, among others. Each holds their own platform feature.

Media

References

01: Alqurashi YD, Nakamura T, Goverdovsky V, et al. A novel in-ear sensor to determine sleep latency during the Multiple Sleep Latency Test in healthy adults with and without sleep restriction. Nat Sci Sleep 2018;10:385-96. PMID 30538591
02: Berry RB. The AASM Manual for the scoring of sleep and associated events. Rules, terminology and technical specifications. Darien: American Academy of Sleep Medicine, 2012.
03: Khosla S, Deak MC, Gault D, et al. Consumer sleep technology: an American Academy of Sleep Medicine position statement. J Clin Sleep Med 2018;14(5): 877-80. PMID 29734997
04: Meltzer LJ, Hiruma LS, Avis K, Montgomery-Downs H, Valentin J. Comparison of a commercial accelerometer with polysomnography and actigraphy in children and adolescents. Sleep 2015;38(8):1323-30. PMID 26118555
05: Papaetis GS. GLP-1 receptor agonists, SGLT-2 inhibitors, and obstructive sleep apnea: can new allies face an old enemy? Arch Med Sci Atheroscler Dis 2023;8:e19-34. PMID 37153372
06: Younes M, Kuna ST, Pack AI, et al. Reliability of the American Academy of Sleep Medicine rules for assessing sleep depth in clinical practice. J Clin Sleep Med 2018;14(2):205-13.** PMID 29351821
07: References especially recommended by the author or editor for general reading.

Contributors

All contributors' financial relationships have been reviewed and mitigated to ensure that this and every other article is free from commercial bias.

Author

Richard P Knudsen MD FAASM CNP FAAP

Dr. Knudsen of Arizona Sleep Center has no relevant financial relationships to disclose.
See Profile

Editor

Antonio Culebras MD FAAN FAHA FAASM

Dr. Culebras of SUNY Upstate Medical University at Syracuse has no relevant financial relationships to disclose.
See Profile

Patient Profile

Population groups selectively affected: snorers

obese patients

insomnia

hypersomnia

dyssomnia
Occupation groups selectively affected: aviation personnel

military personnel

brain workers

This is an article preview.
Start a Free Account
to access the full version.

Nearly 3,000 illustrations, including video clips of neurologic disorders.
Every article is reviewed by our esteemed Editorial Board for accuracy and currency.
Full spectrum of neurology in 1,200 comprehensive articles.
Listen to MedLink on the go with Audio versions of each article.

Questions or Comment?

MedLink®, LLC

3525 Del Mar Heights Rd, Ste 304
San Diego, CA 92130-2122

Toll Free (U.S. + Canada): 800-452-2400

US Number: +1-619-640-4660

Support: service@medlink.com

Editor: editor@medlink.com

ISSN: 2831-9125

Multisensory wearable technology to monitor sleep and circadian rhythms

Associated Disorders

obstructive sleep apnea

Also Relevant

Central sleep apnea
Hypersomnolence
Obstructive sleep apnea
Recurrent hypersomnia

Clinical Categories

Sleep Disorders

Multisensory wearable technology to monitor sleep and circadian rhythms

Multisensory wearable technology to monitor sleep and circadian rhythms

Introduction

Overview

Key points

Discussion

Media

References

Contributors

Author

Editor

Patient Profile

ICD & OMIM codes

This is an article preview.
Start a Free Account
to access the full version.

Questions or Comment?

Also in This Category

Telehealth and cognitive behavioral therapy for insomnia (CBT-I)

NonREM parasomnias

Neurologic disorders associated with obesity

Hypersomnolence

Sleep disorders in women

Sleep, stroke, and vascular dementia

Parasomnia overlap disorder and status dissociatus

Stimulant-dependent sleep disorder

Multisensory wearable technology to monitor sleep and circadian rhythms

Introduction

Overview

Key points

Discussion

Media

References

Contributors

Author

Editor

Patient Profile

ICD & OMIM codes

This is an article preview. Start a Free Account to access the full version.

Questions or Comment?

Also in This Category

Telehealth and cognitive behavioral therapy for insomnia (CBT-I)

NonREM parasomnias

Neurologic disorders associated with obesity

Hypersomnolence

Sleep disorders in women

Sleep, stroke, and vascular dementia

Parasomnia overlap disorder and status dissociatus

Stimulant-dependent sleep disorder

This is an article preview.
Start a Free Account
to access the full version.