LAUSR

Wrist actigraphy is a gold-standard method for estimating sleep patterns in the field. Actigraphy adherence is limited when participants remove the device for daily activities (e.g., showers, exercise). Here we evaluate the validity of a novel water-resistant wearable, the “Actigpatch,” compared to polysomnography and traditional actigraphy. Seven adults (4F; aged 22-54 years [m: 31.1±13.1]) slept in the laboratory for a total of 33 nights. Participants wore a Micro Motionlogger actigraphy (Ambulatory Monitoring Inc., Ardley, NY) on the non-dominant wrist and the Actigpatch—a 0.5in2 circuit board enclosed in a water-resistant adhesive (Circadian Positioning Systems, Newport, RI)—on the triceps. Both devices recorded tri-axial accelerometry, with sleep-wake estimates produced in 1-minute epochs (Sadeh algorithm). Simultaneous PSG data were reduced to 1-minute resolution favoring wake, keeping with recent recommendations. We computed epoch-by-epoch confusion matrices and derived 2 validation parameters: sensitivity (e.g., ability to detect sleep) and specificity (e.g., ability to detect wake). Finally, we compared total sleep time estimates (TST) to evaluate the bias of each device. Nested mixed models (nights within individuals) compared device performance. The Actigpatch demonstrated high sensitivity (.95; 95%CI: [.92 .98]) and specificity (.89; [.86, .91]) against polysomnography. Similar sensitivity (.96; [.94, .99]) and specificity (.84; [.78 .91]) were found comparing the Actigpatch to the Motionlogger. Comparing the devices’ validity with PSG, sensitivity was not statistically different between the Actigpatch and Motionlogger (b=.0041, t=0.56; p=.58); however, the Motionlogger demonstrated higher specificity (.95; [.92, .97]) compared to the Actigpatch (b=0.065, t=4.69; p<.001). To that end, TST estimates were longer (p=.016) for the Actigpatch (449min; [428, 471] relative to the Motionlogger (438min; [416, 459]). These data indicate that the adhesive “Actigpatch” is as sensitive to detect polysomnographic-confirmed sleep as a common research-grade actigraph. The Actigpatch may be less capable of detecting wake episodes. Unlike traditional actigraphs, the Actigpatch can be worn continuously for 3 weeks without risk of water or impact damage. Participants are not responsible for remembering to wear the device. Field studies, or studies in populations struggling with adherence (e.g., children) may benefit from wearable monitors such as the Actigpatch. R01AA025593, Circadian Positioning Systems