Exploration of circadian rhythm characteristics and its impact on prognosis and neuroinflammation in acute ischemic stroke patients

Objective This study evaluated endogenous circadian rhythm characteristics in mild acute ischemic stroke (AIS) patients, their impact on prognosis, and underlying mechanisms.Methods AIS patients were selected from the Department of the Second Affiliated Hospital of Soochow University, and volunteers were recruited as the control group. A phased sampling strategy was used: first, salivary melatonin was collected at 6 daily time points (0:00, 3:00, 6:00, 12:00, 18:00, 21:00) to assess secretion trends; then, hourly samples from 19:00–23:00 were taken to calculate dim light melatonin onset (DLMO). Three-month follow-up was done, and AIS patients were grouped by DLMO to explore links between circadian rhythm and plasma inflammatory markers.Results A total of 255 participants were enrolled in this study, including 182 AIS patients and 73 controls. The melatonin amplitude and peak were lower throughout the day in the AIS group, with a delayed peak secretion time. DLMO, Post-DLMO surge and AUC30 in the AIS group showed a delayed trend. Multivariate logistic regression analysis indicated that DLMO was an independent risk factor for prognosis (p = 0.009). The HIF-1α level in the Delayed DLMO group was higher than that in the Advanced DLMO group (p = 0.004).Conclusion In mild AIS patients, the endogenous melatonin secretion peak decreased, and the time to reach the peak was delayed. A delayed endogenous circadian rhythm might be an independent risk factor for poor prognosis in mild AIS patients, and HIF-1α might be involved in this process.