Many sleep clinicians and researchers are on the market for new actigraphy devices after the discontinuation of Actiwatch support last December.

By Sree Roy

When Society of Behavioral Sleep Medicine president Michael R. Nadorff, PhD, learned that Philips was discontinuing its Actiwatch, he was dismayed. “That was not a good announcement for me as I had invested quite a bit of money in their actigraph line,” he says. 

Nardorff, a professor and director of the clinical PhD program at Mississippi State University’s department of psychology, mostly used the devices for research, though he occasionally used them clinically too. 

“As luck would have it, I had turned in a grant right before the announcement that said we would use those actigraphs, and our score was negatively impacted because the reviewers had rightly realized that we wouldn’t be able to use them,” Nardorff says. (He has since rewritten the grant so it can cover the five-figure expense of purchasing new actigraphs.)

He worries about how other clinicians and researchers will cover the unexpected expense. “I worry there will be some of us who are unable to purchase other watches and will either stop using actigraphy or will use them out of spec since there is no way to get them recalibrated,” he says. (Editor’s note: Ask actigraphy companies for a discount for being a former Actiwatch user; several advised Sleep Review that they are offering such discounts.)

Still, Nadorff stresses other good actigraphy devices are available. “Use it as an opportunity to look at the new features—they have come a long way in recent years—and pick one that fits well with your practice,” he says. “I would encourage people to consult with those using other systems to get a sense of how they like them.

“You may find that the result is an actigraph that is a better fit for your practice; you just didn’t realize since you were previously locked into the Philips system.”

Sleep Review has compiled five such options.

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Actigraph LEAP | Ambulatory Monitoring Micro Motionlogger/SleepWatch 2.0 | Empatica EmbracePlus | SOMNOmedics ​​SOMNOwatch Plus/SOMNOwatch eco | Consumer Wearables via Arcascope 

ActiGraph LEAP

ActiGraph’s newest option, ActiGraph LEAP, can collect physiological signals in addition to movement data, which can provide more information about sleep and circadian rhythm beyond simple actigraphy devices like Actiwatch. 

“Actiwatch was a great product; like our previous models, it served clients well using just an accelerometer,” says Jeremy Wyatt, CEO of ActiGraph. “Our new LEAP device is equipped with multi-sensor technology and provides a wide spectrum of health metrics from a single wrist-worn device.” Its photoplethysmography sensor means it can also provide sleep staging and monitor skin temperature, respiration, and oxygen saturation during sleep, according to Wyatt.

ActiGraph provides the raw data from all its devices, “which is critical for research transparency and longevity,” Wyatt says.

Backward compatibility with Actiwatch: ActiGraph has published a conversion equation to compare Actiwatch counts data to open-source ActiGraph counts.¹ ActiGraph’s team of scientists has also completed two studies evaluating sleep algorithms² and developed a new deep-learning-based algorithm that can work on both Actiwatch counts and ActiGraph counts data.³ Additionally, its data science team can provide support to current or previous Actiwatch users who need help analyzing collected data.

Manufacturer-recommended study: Domain adversarial convolutional neural network improves the accuracy and generalizability of wearable-based sleep assessment technology.³

Ambulatory Monitoring Micro Motionlogger/SleepWatch 2.0

As an actigraphy-only company, Ambulatory Monitoring Inc makes sure its devices are useful and accurate for the sleep industry, says Tom Kazlausky, company president. 

The company’s “secret sauce,” incorporated into the Micro Motionlogger actigraph that it recommends for people seeking an Actiwatch alternative, is in the preprocessing of the signal. The Micro Motionlogger is better than the Actiwatch at catching the small movements that denote events such as wake after sleep onset and sleep efficiency. The Actiwatch discontinuation “leaves the field open for better actigraphy,” Kazlausky says. He recommends that sleep clinicians and researchers ask for actigraph validations before purchasing new devices.

Ambulatory Monitoring is also putting the finishing touches on its soon-to-debut SleepWatch 2.0 actigraph. Kazlausky says, “We’re adding all the bells and whistles that people are used to when playing with sleep trackers,” including Bluetooth connections, cloud software, a photoplethysmography sensor, and a touchscreen with a scroll wheel.

The company expects to offer a full-value trade-in program for people who want to upgrade their Micro Motionlogger to the SleepWatch 2.0 after the new device’s release.

Backward compatibility with Actiwatch: Ambulatory Monitoring provides raw data from its devices. It will not allow other devices to interface with its software.

Manufacturer-recommended study: Comparison of Motionlogger Watch and Actiwatch actigraphs to polysomnography for sleep/wake estimation in healthy young adults.⁴

Empatica EmbracePlus

Empatica’s EmbracePlus device, a component of the company’s full-stack Empatica Health Monitoring Platform, provides more than 120 digital biomarkers, over 100 of which are for actigraphy. The device can be used with Empatica accessories to enable positioning at locations including the wrist, waist, hip, and chest. 

The device is designed to be very comfortable to wear, says Simone Tognetti, Empatica’s chief technology officer. “Last year, on a research expedition to Antarctica to study the impact of extreme weather conditions on metabolism, participants wore EmbracePlus alongside other popular wearables to monitor their physiology. By the end, many of them reported that EmbracePlus was the only one comfortable enough to wear for days on end,” he says.

Compared to the Actiwatch, the EmbracePlus employs a more advanced inertial measurement unit with a better resolution and a higher sampling frequency, Tognetti says. “These features are critical for the evaluation and classification of physical activity. In addition, the ability to leverage all the other vital signs that the EmbracePlus can collect, such as pulse rate and electrodermal activity, can provide an additional layer of insight into the psycho-physiological states of the user, taking into account the activity of the autonomic nervous system and how it impacts—and is impacted by—circadian rhythms,” he says.

“We’ve also intensified our efforts to position EmbracePlus not just as the ideal alternative to Actiwatch but as the wearable of choice for remote health monitoring purposes by focusing on expanding our range of digital measures and investing in hardware enhancements. We are also working on porting third-party algorithms into our platform, creating an even more enriched and complete offering for clinical professionals.”

Backward compatibility with Actiwatch: High-frequency raw data is provided, together with a list of validated metrics on sleep and physical activity. Having access to this level of granularity allows using the Empatica Health Monitoring Platform to collect longitudinal signals and apply an array of algorithms for the data processing phase, including the models developed and published by Philips, for a wider analysis using the model that best fits each researcher’s needs.

Manufacturer-recommended study: Sleep assessment by means of a wrist actigraphy-based algorithm: Agreement with polysomnography in an ambulatory study on older adults.⁵

SOMNOmedics ​​SOMNOwatch Plus/SOMNOwatch eco

L. Janson Lanier, SOMNOmedics director of sales – Western US, recommends two options for sleep clinicians and researchers seeking Actiwatch alternatives. 

The first is the SOMNOwatch Plus, which sleep and circadian experts have used for more than 20 years. “The SOMNOwatch Plus has the benefit of adding additional sensors to record additional signals,” he says. The second, for pure actigraphy, is the company’s newly developed SOMNOwatch eco, which equals the Actiwatch specifications but with a longer runtime.

“Both devices are small, lightweight, easy to use, and are as comfortable to wear as a watch,” Lanier says. “They are powerful multichannel recorders for actigraphy (3-axel accelerometer), movement, and body position. They encase an ambient light sensor and a patient-marker button with acoustic tone.”

According to Lanier, the SOMNOmedics actigraphs have several advantages over the Actiwatch: SOMNOwatch Plus allows for the attachment external sensors to record more signals, potentially replacing several devices (such as a periodic limb movements recorder); SOMNOwatch can be attached to the ankle instead of the wrist for limb movement detection; and the high-frequency acquisition of movement data with a sample rate of 256 Hz can be used to record tremor intensity and frequency over a longer period. “This is useful for the assessment and treatment of Parkinson’s disease,” he says.

Backward compatibility with Actiwatch: SOMNOmedics systems can only be used with the company’s DOMINO Light software. “We are looking into the possibility of importing AWD files into our software, so you can still open old Actiwatch files,” Lanier says, adding, “We do not recommend customers use a software that is no longer supported by the manufacturer. This could lead to security threats that will not be solved because Philips no longer supports the software and will not make any updates.”

Manufacturer-recommended study: AASM standards of practice compliant validation of actigraphic sleep analysis from SOMNOwatch^TM versus polysomnographic sleep diagnostics shows high conformity also among subjects with sleep disordered breathing.⁶

Consumer Wearables via Arcascope 

A sleep researcher by training, Olivia Walch, PhD, is ever practical. Since actigraphy has yet to be consistently reimbursed by third-party payors, Walch realized that to achieve some of the value of actigraphy but without the cost, a solution is to use devices that people are already willing to pay for out of pocket—their consumer wearables.

Arcascope, where Walch is CEO, uses consumer wearable data to help specific demographics, primarily shift workers, improve their health by boosting their circadian rhythms. But she’s found an important side business in helping sleep researchers pull the raw data off consumer wearables, including the Apple Watch and Android Wear-compatible watches (which includes the Samsung Galaxy). With the discontinuation of the Actiwatch, she anticipates inquiries from clinicians too.

Arcascape can pull the raw acceleration data off these consumer wearables. “Raw acceleration is nice because it’s not a propriety number. It’s not trademarked,” Walch says. She also pulls other data streams, such as heart rate variability, though those are trickier as the calculations are specific to the device manufacturer, which can change its formula over time.

While apps such as Apple Health allow consumers and clinicians to view a single night of sleep data, “if you want to export that to a CSV file, It’s not easy to do,” Walch says. “You want someone who’s written code to help you do it.”

Arcascape charges a flat fee plus a per-seat cost to pull the raw data. 

Backward compatibility with Actiwatch: “We give customers the raw data and simultaneously a processed version of it using open-source algorithms,” Walch says. “So they don’t have to apply the algorithm to the raw data themselves, but if they want to apply a new algorithm to it in the future, they have it.”

Manufacturer-recommended study: Arcascope is submitting a paper to a peer-reviewed journal next month showing the backward compatibility of Apple Watch data to the Actiwatch.

References

1. Lee PH, Neishabouri A, Tse ACY. Guo CC. Comparative analysis and conversion between Actiwatch and ActiGraph open-source counts. J Meas Phys Behav. 2023 Aug;7(1):jmpb.2022-0054.

2. Patterson MR, Nunes AAS, Gerstel D, et al. 40 years of actigraphy in sleep medicine and current state of the art algorithms. NPJ Digit Med. 2023 Mar 24;6(1):51

3. Nunes AS, Patterson MR, Gerstel D. Domain adversarial convolutional neural network improves the accuracy and generalizability of wearable-based sleep assessment technology. Preprint. 13 Dec 2022.

4. Rupp TL, Balkin TJ. Comparison of Motionlogger Watch and Actiwatch actigraphs to polysomnography for sleep/wake estimation in healthy young adults. Behav Res. 2011 Dec;43:1152–60.

5. Regalia G, Gerboni G, Migliorini M, et al. Sleep assessment by means of a wrist actigraphy-based algorithm: agreement with polysomnography in an ambulatory study on older adults. Chronobiol Int. 2021 Mar;38(3):400-14.

6. Dick R, Penzel T, Fietze I, et al. AASM standards of practice compliant validation of actigraphic sleep analysis from SOMNOwatch™ versus polysomnographic sleep diagnostics shows high conformity also among subjects with sleep disordered breathing. Physiol Meas. 2010 Dec;31(12):1623-33.

Top photo: SOMNOmedics SOMNOwatch eco