0617 Tracking circadian phase for personalized schedules: A precise medical approach to reduce circadian misalignment in shift workers

Abstract Introduction Night shift workers experience symptoms of excessive sleepiness and insomnia due to misalignment between the work schedule and their circadian clock. Circadian misalignment can be corrected using exposure to bright light delivered in accordance with a phase response curve. Given the high variability of circadian phase in night shift workers, using a one-schedule-fits-all approach to light therapy might result in significant error (e.g., phase shifts in the wrong direction). Instead, a personalized light exposure schedule should result in more consistent and precise phase shifts. This randomized controlled trial compared personalized and non-personalized light schedules in shifting circadian phase in night shift workers. Methods Individuals with shift work disorder (ICSD-3 diagnostic criteria) were randomized into two conditions: personalized light therapy, or non-personalized light therapy control. Personalized light schedules were based on estimates of dim light melatonin onset (DLMO) derived from mathematical modeling of activity data collected via an Apple Watch. Estimates were confirmed with in-lab DLMO. Light schedules were delivered through a mobile app (SHIFT) that updated in accordance with real-time estimates of DLMO. Participants were provided a light box as a source of bright light at night and light blocking glasses. Phase shifts were determined based on in-lab DLMO measured before and after treatment. Results Those who received personalized light therapy treatment achieved a larger phase delay (Mean = 7.37 hours, SD = 3.03 hours) compared to those in the non-personalized light therapy control group (Mean = 0.84 hours, SD = 3.46 hours), t(5) = 2.501, p = 0.05. Conclusion Preliminary results suggest that personalized light therapy may be a more effective treatment to correct circadian misalignment in night shift workers by delivering treatment according to each individual’s unique circadian phase. This has implications for improving the symptoms of shift work disorder and quality of life for this population. Support (if any) Support for this study was provided from the National Institute of Health R41HL163783 and the American Academy of Sleep Medicine Foundation (245-SR-21) awarded to Dr. Philip Cheng.