Abstract
BACKGROUND: Emerging evidence indicates chronic nighttime light (NTL) exposure elevates cerebrovascular risk, while its pathophysiological implications for broader cardiometabolic diseases (CMD) remain inadequately characterized. This investigation examines longitudinal associations between sustained NTL exposure and incident CMD progression, with particular focus on potential mediation of cardiometabolic multimorbidity (CMM) development. METHODS: The data of this study were obtained from the UK Biobank (n = 502,493). CMM was operationalized as concurrent diagnosis of ≥ 2 distinct CMD. NTL exposure data was obtained from the National Earth System Science Data Center. We implemented multi-state models to quantify NTL-associated transition probabilities between disease-free, CMD, CMM and death states. RESULTS: Among the 391,549 participants, during a median follow-up period of 14.6 years, 55,602 participants developed first cardiometabolic disease (FCMD) and 8,053 participants progressed to CMM. At the 10-year follow-up, the probabilities were 87.69% for Baseline, 7.65% for FCMD, 0.91% for CMM, and 3.75% for Death, respectively. Study participants were divided into 5 equal groups by NTL exposure level (Q1-Q5). Results showed that the highest exposure group (Q5) had a median NTL of 25.51 nW/cm²/sr (interquartile range [IQR]: 10.23), while the lowest (Q1) had 1.50 nW/cm²/sr (IQR: 2.29). The median NTL of Q5 was 17.0-fold that of Q1. NTL exposure was associated with small increases of FCMD, CMM, and death. Within the pathway from baseline to FCMD in the multi - state model, Q4 and Q5 showed statistical significance relative to Q1. Their respective hazard ratios (HRs) were 1.07 (1.02, 1.12) and 1.10 (1.05, 1.16). Regarding the pathway from FCMD to CMM, the adjusted hazard ratios demonstrated a progressive elevation across successive exposure tiers: 1.03 (0.95, 1.10) for Q1, ascending to 1.08 (1.01, 1.16), 1.11 (1.03, 1.19), and 1.16 (1.08, 1.25) for subsequent quintile increases. CONCLUSIONS: NTL exposure was associated with small increases of CMD. The higher the degree of exposure to NTL, the correspondingly higher the risks of developing into CMM.