Impact of melatonin administration and sleep duration on arterial parameters in climacteric workers: a phase II, randomized, placebo-controlled, double-blind pilot clinical trial comparing work shifts

Women working night shifts are exposed to light during usual sleep hours, reducing melatonin production. Since melatonin benefits cardiometabolic function, low levels may relate to cardiovascular diseases. Another risk factor is the climacteric period, when declining estrogen reduces cardiovascular protection. This study evaluated melatonin’s effects on blood pressure and arterial stiffness in climacteric female shift workers, considering sleep duration. A phase II, randomized, placebo-controlled, double-blind pilot trial was conducted with 24 women divided into three groups according to work shift: morning, afternoon and night. The melatonin group showed a 20.8% reduction in the Augmentation Index (AIx), while the placebo group increased 69.9% (p < 0.002) after adjustment for brachial systolic blood pressure (BSBP). Significant effects of melatonin and sleep duration were observed for AIx and brachial and central blood pressure, irrespective of work shift. An interaction between group and sleep duration was found for BSBP and work shift: AIx decreased 26.5% in the melatonin group with < 7 hours of sleep and increased 803.6% in the placebo group (p < 0.001). Melatonin combined with longer sleep improved blood pressure and arterial stiffness, with greater benefits for night-shift workers. The findings suggest melatonin may mitigate cardiovascular effects of chronic circadian desynchronization among night-shift workers. REBEC:RBR-10whktxm