Association between light exposure patterns and multidimensional health outcomes in individuals with myalgic encephalomyelitis/chronic fatigue syndrome: findings from an observational cross-sectional cohort study.

Publication date: Jul 03, 2026

Light is a major environmental factor regulating circadian rhythms, sleep- wake cycles, and mood-related behaviors. Patients with Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) often experience circadian disruption and poor sleep quality, which severely compromise their quality of life; however, the relationship between light exposure and illness severity remains largely unknown. An observational cross-sectional cohort secondary study used collected data from 100 ME/CFS patients and 56 healthy controls to explore the impact of spontaneous light exposure on multidimensional health status and circulating biochemical parameters. Demographic and clinical features were assessed using validated patient-reported outcome measures. Light intensity, wrist temperature, and physical activity were continuously monitored at home over one week using wrist-worn actigraphy. Light intensity during predefined intervals and rhythmic variables of light cycle were calculated. Principal component analysis (PCA) was applied to reduce dimensionality of light variables. Multivariable analysis was performed adjusting for age, sex, body mass index, and physical activity. Following PCA of the light patterns, two components emerged across groups with high consistency: PC1 (explaining 61. 7% of the total variance) reflected higher daytime light and rhythm stability, and PC2 (explaining 16. 1%) represented nocturnal/early-morning light and rhythm instability. In ME/CFS patients, light variables were more extensively associated with clinical outcomes measures (FIS-40, PSQI and SF-36) than in healthy controls (all p 

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Semantics

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