Background: Exposure to short-wavelength (blue) light has increased substantially with the widespread use of light emitting diode (LED) lighting and digital devices. Understanding the health implications requires a research framework centered on the human opsin system. Several blue-light–responsive opsins—including OPN1 (cones), OPN3 (encephalopsin), OPN4 (melanopsin), OPN5 (neuropsin)—mediate both visual and non-visual pathways that regulate circadian entrainment, melatonin release, sleep–wake patterns, hormonal rhythms, and retinal physiology. Emerging evidence suggests that chronic disruption of these pathways may contribute to sleep disturbance, impaired wellbeing and also metabolic dysregulation, including increased risk of Type 2 diabetes. However, little is known about how real-world “spectral diets” interact with these opsin-driven mechanisms or how such exposures manifest in retinal structural or microvascular biomarkers detectable with optical coherence tomography (OCT) and OCT angiography (OCTA).
Aims: This study will characterise the real-life spectral diet of adults working and studying in a university environment and to examine how blue-light exposure patterns relate to circadian regulation, wellbeing, and ocular-health indicators. Objective environmental light-data will be obtained using light dosimeters (LYS/LiDo), which will provide detailed measures of spectral composition, timing, duration, intensity, and cumulative exposure. These data will be integrated with sleep and behavioural metrics collected via validated questionnaires and wrist-worn wearables. Retinal OCT/OCTA imaging will be used to assess macular structure, retinal microvasculature, and potential early biomarkers of light-related stress.
Hypothesis: Preliminary data from 14 participants suggest that higher exposure to blue-enriched light in the morning is linked to increased deep sleep duration, whereas greater evening and nighttime blue-light exposure is associated with reduced rapid eye movement sleep; this link may extend to ocular health.
Objectives: This study will examine associations between spectral exposure and physiological outcomes mediated through OPN1-, OPN3-, OPN4-, and OPN5-related pathways, with a focus on both visual and non-visual consequences and potential links to metabolic health.