Association between light exposure patterns and multidimensional health outcomes in individuals with myalgic encephalomyelitis/chronic fatigue syndrome: findings from a prospective cohort study
Background
Light is a major environmental factor regulating circadian rhythms, sleep-wake cycles, and mood-related behaviors. Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) often experience circadian disruption and poor sleep quality which compromise quality of life; however, the relationship between light exposure and illness severity remains largely unknown.
Methods
A prospective, cohort secondary study included existing data from 100 ME/CFS patients and 56 healthy controls to explore impact of spontaneous light exposure on multidimensional health status and circulating biochemical parameters among participants. 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 in the participants. 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. A multivariable analysis adjusting for age, sex, body mass index, and activity was performed.
Results
After PCA analysis of the light patterns, two components emerged among the groups with high consistency across replicates: PC1 explained 61.7% of the total variance reflected higher daytime light and rhythm stability, and PC2 explained 16.1% represented nocturnal/early-morning light and rhythm instability.
In ME/CFS, light variables were more extensively associated with outcomes measures (FIS-40, PSQI and SF-36) than in healthy controls (all p < 0.05), and PC2 was associated with higher levels of VCAM-1 and triglycerides and lower serotonin concentration (all p < 0.05).
Moreover, four distinct light patterns were identified based on PCA scores (nocturnal light, healthy, adverse, and low diurnal light). ME/CFS patients with the healthy light pattern showed lower fatigue, sleep complaints and autonomic dysfunction and higher quality of life compared to those with the adverse light pattern (all p < 0.05).
No significant differences were observed among healthy controls.
Conclusions
Light exposure patterns show distinct associations with symptom variability in ME/CFS compared with healthy controls. More stable daytime light appears to relate to better symptom profiles, whereas irregular exposure and nocturnal light are linked to poorer health outcomes.
Although causality cannot be inferred, these findings highlight light exposure as a potentially modifiable and non-invasive target for behavioral interventions aimed at improving quality of life of ME/CFS, which may represent an emerging area for future research.
Web | DOI | PDF | Research Square | Preprint
Cambras, Trinitat; Domingo, Joan Carles; Sanmartin-Sentañes, Ramon; Alegre-Martin, Jose; Castro-Marrero, Jesus
Background
Light is a major environmental factor regulating circadian rhythms, sleep-wake cycles, and mood-related behaviors. Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) often experience circadian disruption and poor sleep quality which compromise quality of life; however, the relationship between light exposure and illness severity remains largely unknown.
Methods
A prospective, cohort secondary study included existing data from 100 ME/CFS patients and 56 healthy controls to explore impact of spontaneous light exposure on multidimensional health status and circulating biochemical parameters among participants. 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 in the participants. 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. A multivariable analysis adjusting for age, sex, body mass index, and activity was performed.
Results
After PCA analysis of the light patterns, two components emerged among the groups with high consistency across replicates: PC1 explained 61.7% of the total variance reflected higher daytime light and rhythm stability, and PC2 explained 16.1% represented nocturnal/early-morning light and rhythm instability.
In ME/CFS, light variables were more extensively associated with outcomes measures (FIS-40, PSQI and SF-36) than in healthy controls (all p < 0.05), and PC2 was associated with higher levels of VCAM-1 and triglycerides and lower serotonin concentration (all p < 0.05).
Moreover, four distinct light patterns were identified based on PCA scores (nocturnal light, healthy, adverse, and low diurnal light). ME/CFS patients with the healthy light pattern showed lower fatigue, sleep complaints and autonomic dysfunction and higher quality of life compared to those with the adverse light pattern (all p < 0.05).
No significant differences were observed among healthy controls.
Conclusions
Light exposure patterns show distinct associations with symptom variability in ME/CFS compared with healthy controls. More stable daytime light appears to relate to better symptom profiles, whereas irregular exposure and nocturnal light are linked to poorer health outcomes.
Although causality cannot be inferred, these findings highlight light exposure as a potentially modifiable and non-invasive target for behavioral interventions aimed at improving quality of life of ME/CFS, which may represent an emerging area for future research.
Web | DOI | PDF | Research Square | Preprint
