Circadian Light Hygiene Is Associated with Anemia Markers in Young Adults.

BACKGROUND

Light exposure (LE) and its influence on circadian rhythms are recognized to impact various physiological domains, yet their specific associations with hematological status, particularly in high-latitude environments, remain underexplored. Understanding these links could offer insights into maintaining hematological health.

METHODS

This study investigated the relationship between 24 h light exposure (LE), blue light exposure (BLE), sleep, and physical activity (PA) and hematological markers in 85 young adults (18-25 years). Participants underwent simultaneous 7-day monitoring using actigraphy and RGB sensors, coupled with morning blood sampling for hemoglobin (HGB), hematocrit (HCT), mean corpuscular hemoglobin (MCH), and red blood cell distribution width (RDW-CV).

RESULTS

Univariate analyses revealed significant correlations: normalized BLE amplitude (NA BLE) positively correlated with HGB (r = 0.369, p = 0.001) and MCH (r = 0.378, p < 0.001). A later BLE acrophase correlated with lower HGB and MCH, but higher RDW-CV. Later PA acrophase was associated with lower MCH and higher RDW-CV, while later bedtime correlated with lower HGB and MCH. Multivariate regressions confirmed that a larger NA BLE predicted higher HGB (β = 0.206, p = 0.037) and MCH (β = 0.377, p < 0.001), and an earlier BLE acrophase predicted higher MCH and smaller RDW-CV.

CONCLUSIONS

Advantageous circadian patterns of BLE and PA are linked to a favorable hematological status in young adults during the light-deficient fall season at higher latitudes, underscoring the importance of optimizing light and activity timing for hematological health.