Light exposure significantly impacts mood, with several large-scale studies demonstrating the positive effects of daytime light exposure on mood. Studies have also found that light’s impact on mood might be indirect, through its effects on sleep and biological rhythms regulation. However, there is still a lack of compelling large-scale studies that confirm the mediation effect of sleep-related variables in the association of light exposure and mood. We aim to use objectively-measured, naturalistic data to calculate the mediating effect of sleep regularity between light exposure and mood.
Aim 1 will be calculating light exposure variables (duration, intensity, and rhythmicity) using the raw actigraphy data from UK Biobank participants. Data will be processed using “GGIR” – an open source R package for accelerometer – and sleep regularity and light exposure will be computed using custom-built R functions.
Aim 2 will be evaluating the mediating effect of sleep regularity between light exposure and mood. Depressive symptoms from the previously analyzed actigraphy-wearers can be obtained from the UK Biobank’s questionnaire data. The Average Causal Mediation Effect can be calculated using R’s “mediation” package.
This project is part of a larger study repeating the same analysis in another large population (the National Health and Nutrition Examination Survey) and a clinical population via the ENABLE platform (clinicaltrials.gov ID: NCT06408012). By investigating two independent populations and a clinical sample, we will have much higher confidence that we have precisely defined the impact sleep regularity has between light exposure and mood.