Real-world translation of a dynamic and personalized intervention for shift workers

PROJECT SUMMARY Shift workers experience profound circadian disruption, which can have deleterious long term effects on their health and quality of life. Due to the necessity of night shift work for 24-7 continuous operations and safety, it is urgent that society prioritize ways to support shift worker health. Mood, fatigue, and performance can be improved in shift workers by shifting the timing of production of the hormone melatonin outside the hours they are expected to work. This can be achieved with a targeted lighting intervention, as light is the primary input to the body’s circadian clock, and supported by behavioral interventions, including meal and exercise timing. Crafting such an intervention for an individual, however, requires knowledge of the person’s current biological time, or circadian state, which has traditionally been extremely challenging to assess in shift workers. The gold standard measure of circadian timing is dim light melatonin onset, or DLMO. For day workers, DLMO most commonly occurs in a six hour window prior to habitual bedtime. For fixed night shift workers, however, DLMO can occur anytime over the 24-hour day. This requires 24 hours of melatonin collection in order to arrive at a single indicator of internal time, which is often prohibitively time consuming and expensive. The small business on this proposal, Arcascope, has developed new techniques for noninvasively predicting circadian timing through consumer wearable devices (e.g. Apple Watch) in collaboration with research partner organization Henry Ford. These techniques can accurately predict DLMO timing in shift working adults using consumer wearable devices. The PIs of this grant have also developed mathematical techniques for generating lighting recommendations based on predicted circadian timing, aimed at shifting the peak circadian drive to sleep outside the window of working hours. These techniques have been evaluated in a Phase I STTR, through the deployment of an iOS mobile app, SHIFT, which achieved large phase shifts in real world night shift workers, demonstrating that it is possible to shift their circadian rhythms so that the melatonin secretion occurs outside their working hours. The next step in this work is to move beyond feasibility and towards effectiveness and implementation. In particular, it remains to be demonstrated that the mobile app can produce meaningful changes in stakeholder-centered outcomes in large, rigorously tested cohorts. These outcomes include not only worker health outcomes, such as depression and sleep health, but also quantities of critical import to their employers finances, including worker turnover, safety, and health coverage costs. In this Phase II project, we propose to evaluate how the SHIFT app can affect these outcomes, demonstrate noninferiority of an Android version, and assess key facilitators and barriers to engagement and implementation.