You are here

Novel Fieldable Device for Detection of Sleep Microarousals


OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Military Operational Medicine OBJECTIVE: Develop a fieldable, wearable device that detects microarousals during sleep. DESCRIPTION: It is well known that Soldiers consistently fail to obtain the 7-9 hours of nightly sleep that is recommended by National Sleep Foundation (Watson et al., 2015). In fact, more than 62% of Soldiers average less than 6 hours of sleep per night (Troxel et al., 2015). This is over double what is found in the civilian population, as 28% of civilians average less than 6 hours of sleep per night, thus, a majority of Soldiers are chronically sleep restricted– a situation that reduces the military’s competitive edge. Sleep loss of this magnitude negatively impacts virtually every aspect of performance, health, and readiness. However, even in carefully controlled laboratory studies of sleep loss in health young adults, there exists a spectrum of responses to the same amount of sleep loss, such that roughly 1/3 are resilient to sleep loss and another third are more vulnerable as measured by next day performance (Reifman et al., 2018). Therefore, total sleep time itself does not fully predict performance even in tightly controlled laboratory studies. Additionally, outside of the laboratory, military members encounter many disruptions to sleep, including noise, light, and extreme and fluctuating temperatures. These disruptions are only expected to intensify during multi-domain operations where the battlefield will be progressively more lethal and complex. However, currently available fieldable sleep measurement devices (e.g., watches from Garmin, Fitbit, Apple and rings from Oura) struggle to fully capture smaller disruptions to sleep continuity and can only provide reliable total sleep time measures (Chinoy et al., 2021). For these reasons, there exists a need for a fieldable, wearable device than can measure more than total sleep time. Both the DoD and the consumer market need an unobtrusive, wearable device that can reliably measure sleep continuity – a metric that may predict next day performance and health associated outcomes better than total sleep time. One measure of disrupted sleep continuity is the accumulation of cortical microarousal events across a sleep period. These are moments of brief biological waking activity with a rapid return to sleep (< 15 seconds). These events are not detected with current wearable sleep tracking technology (e.g., watches and rings) but they provide an important datapoint associated with altered daytime functioning (Martin et al., 1996; Stepanski et al., 1987) and negative health outcomes including cardiovascular health and increased diabetes risk (Taylor et al., 2016; Stamatakis and Punjabi 2010). Currently microarousals can only be identified by a trained technologist using polysomnographic equipment in a laboratory setting. However, with the increasing sophistication of wearable devices, including dry electroencephalographic electrodes and increased onboard processing power, it stands to reason that consistent measurement of microarousals could be possible with a fieldable wearable device. This proposal aims to first develop a novel wearable device that measures sleep microarousals in Phase I and then validate the device and determine if microarousals collected by the device are related to next day performance on militarily relevant outcomes in Phase II. If fielded, the technology may require secured communication methods. PHASE I: The objective is to develop a novel wearable device that measures sleep microarousals. The current sleep measurement devices that are on the market can only accurately predict total sleep time and struggle to capture issues with sleep continuity. No current wearable devices can measure microarousals during sleep to our knowledge. Therefore, there is a need for a fieldable device that can measure this important aspect of sleep that is associated with negative health outcomes and altered daytime functioning. This phase will demonstrate the feasibility of producing a demonstration of microarousal detection on a wearable device. Requirements for Phase I device: • Wearable on the body (e.g., placed on the forehead or on a limb) • Comfortable and unobtrusive – should not interfere with sleep • No user interaction needed (e.g., prepping skin, adding electrodes, adding gel) – device should be able to put on by user and then left alone • Wireless – small rechargeable battery lasting at least 12 hours (lithium ion is minimum standard) • Ability to toggle between saving data on device or wirelessly transmitting to local device using military telecommunication standards • Onboard detection of microarousals in real-time – preliminary design and validation can be completed with simulated data PHASE II: The objective is to demonstrate that sleep microarousals can be detected with a novel wearable device and determine feasibility for prediction of next day cognitive performance. This phase will involve testing of the microarousal device created in Phase I to prove it can be used to reliably measure microarousals during sleep. Additionally, performers should determine if microarousals measured during sleep by the device are found to relate to next day cognitive performance. During this phase, performers will build off the results from Phase I and execute human subject research prototype development where participants wear the novel microarousal detection device overnight and then perform militarily relevant tasks the next day. Requirements for Phase II human subject research prototype development: • Overnight PSG recordings collected during sleep while individual is wearing device developed in Phase I • Cognitive performance must be tested the next day following the sleep recording • Cognitive performance datasets should include at least one militarily relevant outcome metric and must contain a measure of vigilance (can count as militarily relevant outcome) • Data should come from healthy adults under 50 (i.e., surrogates of the active duty population including leaders) • Data should be collected on at least 20 individual adults • Data from the device should be able to detect American Academy of Sleep Medicine (AASM) defined microarousals with 85% accuracy compared to polysomnography ( • Data from the device should be tested to ascertain if it can predict next day cognitive performance with 85% accuracy and is significantly better at predicting performance than using total sleep time alone. Performers should provide a statement assessing the feasibility of the device for the prediction of next day performance and any recommendations for follow-up validation studies. Following the conclusion of Phase II, four prototype devices and associated datasets containing the requirements listed above should be delivered to the DoD. PHASE III DUAL USE APPLICATIONS: Following successful completion of Phase II, a fieldable device that can measure sleep microarousals will be available. If preliminary feasibility testing in Phase II indicates that the device has the potential to predict next day cognitive performance, further validation testing will occur in Phase III to verify that the device can reliably predict next day cognitive performance. This device holds great utility in both the commercial market and within the DoD. Commercially a device of this nature would be a game changer for companies that rely on the current state of performance modeling to schedule workers with high risk jobs such as pilots, truck drivers, and law enforcement. Current performance models rely on total sleep time which does not accurately reflect the quality of sleep and therefore does not accurately predict performance. These companies could easily give workers the microarousal detection device to wear during sleep and utilize data from the device to make scheduling decisions. Indeed, employee tracking to increase productivity is becoming more and more accepted in industry ( Additionally, outside of industry commercialization, the rapidly growing sleep device consumer market would embrace this device as a more accurate way to measure sleep and also test the efficacy of different sleep interventions within the home. Software and algorithms developed under this SBIR could also potentially be applied to existing wearable devices and sold and licensed as a severable entity. Applications within the DoD are similar to industry but also the information provided by this device could potentially be incorporated into the MRDC-developed 2B-Alert Performance Prediction algorithm to replace the current app’s onboard reaction time test (i.e., the Psychomotor Vigilance Test, PVT) that provides individualized performance prediction. This would be a large improvement because the PVT requires the user to interface with the app directly to take the test multiple times a day. The device proposed here is a non-invasive and passive wearable. The technology created with this SBIR could also potentially be integrated into existing wearables and scheduling tools, such as 2B-Alert. REFERENCES: 1. Chinoy, E. D., Cuellar, J. A., Huwa, K. E., Jameson, J. T., Watson, C. H., Bessman, S. C., Hirsch, D. A., Cooper, A. D., Drummond, S. P. A., & Markwald, R. R. (2020). Performance of seven consumer sleep-tracking devices compared with polysomnography. In Sleep (Vol. 44, Issue 5). Oxford University Press (OUP). 2. Martin SE, Engleman HM, Deary IJ, Douglas NJ. The effect of sleep fragmentation on daytime function. Am J Respir Crit Care Med. 1996;153(4 Pt 1):1328-1332. doi:10.1164/ajrccm.153.4.8616562 3. Reifman, J., Ramakrishnan, S., Liu, J., Kapela, A., Doty, T. J., Balkin, T. J., Kumar, K., & Khitrov, M. Y. (2018). 2B‐Alert App: A mobile application for real‐time individualized prediction of alertness. In Journal of Sleep Research (Vol. 28, Issue 2). Wiley. 4. Stamatakis, K. A., & Punjabi, N. M. (2010). Effects of Sleep Fragmentation on Glucose Metabolism in Normal Subjects. In Chest (Vol. 137, Issue 1, pp. 95–101). Elsevier BV. 5. Stepanski E, Lamphere J, Roehrs T, Zorick F, Roth T. Experimental sleep fragmentation in normal subjects. Int J Neurosci. 1987;33(3-4):207-214. doi:10.3109/00207458708987405 6. Taylor, K. S., Murai, H., Millar, P. J., Haruki, N., Kimmerly, D. S., Morris, B. L., Tomlinson, G., Bradley, T. D., & Floras, J. S. (2016). Arousal From Sleep and Sympathetic Excitation During Wakefulness. In Hypertension (Vol. 68, Issue 6, pp. 1467–1474). Ovid Technologies (Wolters Kluwer Health). 7. Troxel, W.M., (2015). Sleep Problems and Their Impact on US Service members. Rand Corp, 180(1), 4–6. 8. Watson, N.F. (2015). Recommended amount of sleep for a healthy adult: A joint consensus statement of the American Academy of Sleep Medicine and the Sleep Research Society. Journal of Clinical Sleep Medicine, 11(6), 591-592. KEYWORDS: Sleep, Performance, Wearable, Device, Total Sleep Time, Microarousal
US Flag An Official Website of the United States Government