Abstract
Background: Bright daytime light exposure is important for health and wellbeing and can protect against the consequences of mistimed evening light exposure. Office workers typically work indoors, with limited access to bright daytime light. Although structural lighting solutions and interventions exist, these are limited by the behaviour of the individual. It is currently unknown whether behaviour can be modified to increase bright daytime light exposure.
Methods: 39 healthy office workers (25-45 years), living and working within the Oxford Ring Road (UK) full-time, were enrolled into a 4-week real-world pilot RCT. Participants were matched in pairs based on age, gender, and global PSQI scores. From within these pairs, participants were randomised to either the intervention or control group on a 1:1 basis. The intervention group received light reminder nudges, while the control group received placebo random-word reminder nudges; these were delivered as app-based notifications. Using Condor ActTrus actigraph devices (Condor, São Paolo, Brazil), light exposure was measured as wrist-referenced photopic illuminance (lux). Our primary objectives were to descriptively assess the feasibility and acceptability of the intervention and procedures. Participants and outcome assessors were blind to group assignments.
Results: Overall, the acceptability and feasibility of the study procedures and intervention were good. Outcomes pertaining to the minimisation of bias were successful (blinding, contamination, and co-intervention), and missing data was minimal. Intervention fidelity, however, was suboptimal. On average, participants read ~60% of the nudge notifications. Further analysis revealed differences driven by device type; Android users read a mean percentage of 76.32 ± 27.77% of the nudges, whilst iOS users read 50.40 ± 17.23%. Light data was also collected, but analysis of this data is currently blinded; this data may be available by the time of the conference.
Conclusions and implications: A definitive main trial is both feasible and acceptable with modification to intervention delivery. This trial introduces a novel approach to modifying daytime light exposure, in an app-based format that is both inexpensive and scalable.