Use of Apple Watch to Optimize Light Therapy and Reduce Circadian Misalignment for Night Shift Workers
Recommended Citation
Treger M, Pockrass A, Peeran I, Van Rossen V, Wernette E, Drake C, Walch O, Cheng P. Use of Apple Watch to Optimize Light Therapy and Reduce Circadian Misalignment for Night Shift Workers. Sleep 2025; 48:A383-A384.
Document Type
Conference Proceeding
Publication Date
5-19-2025
Publication Title
Sleep
Abstract
Introduction: Circadian misalignment can be alleviated with targeted light interventions. However, general “light at night” interventions do not account for shift workers’ variable circadian phases. Recently, our lab validated Apple Watch (AW) as a noninvasive means of predict ing circadian timing (i.e. dim light melatonin onset, DLMO). Here, we extend this by examining the clinical utility of AW in informing circadian interventions. We hypothesized the AW-informed group would result in higher rates of circadian alignment following treat ment vs the control (non-personalized) group. We also compared the magnitude of phase shifts between these interventions. Methods: Participants (N=46) were randomly assigned to either the AW or control group, and DLMO was measured before and after treatment. AW data (accelerometer and heart rate) was collected over 2 weeks and processed through a biomathemat ical model of the human circadian system to produce estimated DLMOs. Light therapy schedules were created from the corre sponding phase response curves and implemented with light boxes and blue-blocker glasses (at-home or in-lab) to induce phase shifts. Participants in the control group followed a non-personalized light schedule (light from 18:00 and 21:00; light avoidance from 04:00 and 10:00). Circadian alignment was operationalized as DLMO between 02:00 and 14:00, and a relative risk ratio was used to com pare the rate of circadian alignment between the two groups. Results: The rate of circadian alignment post-treatment was 2.6 times higher in the AW group (56.8%) compared to the control group (22.2%). Additionally, those in the AW group achieved phase delays that were 8.5-times greater than the control group (AW group: delay of 2.5 hours ± 5.0 SD; control group: 0.3 hours ± 4.0 SD). Conclusion: These findings support the use of AW to generate personalized light treatments. Accessible and effective circadian treatments are key to improving the safety of nightshift workers. In the future we aim to perform sensitivity analyses and compare the efficacy of personalized light interventions at-home versus in-lab, to establish the feasibility of prescribing personalized light therapy as an at-home treatment option.
Volume
48
First Page
A383
Last Page
A384
