Introduction
JETLAG, ARTERIAL STIFFNESS
The discrepancy in sleep–wake timing between workdays and free (non-work) days due to modern work schedules possibly causes mild circadian misalignment between endogenous circadian rhythm and the sleep schedule imposed by social obligations. This jetlag-like phenomenon is called “social jetlag (SJL),” [In humans, blood pressure (BP) shows circadian variations; it decreases during sleep and increases in the morning [Thus, the purpose of the present study was to investigate the acute effects of SJL on morning BP surge. As an unhealthy lifestyle on free days, such as excess intake of energy as well as reduced physical activity levels, may confound the effects of SJL, we designed a randomized crossover trial to eliminate these potential confounding effects. We hypothesized that even acute SJL augments morning BP surge. Furthermore, the present study evaluated the effects of acute SJL on other cardiovascular variables and the autonomic nervous system, such as central arterial stiffness and sympathetic nerve activity in a vessel, to elucidate the underlying physiological mechanisms of the morning BP surge due to acute SJL.