Cold-Induced Hypertension as Life-Environment Disease in Winter: Focus on Data From Japan.

An increase in the rate of cardiovascular events (eg, myocardial infarction, stroke, heart failure) during the winter season has been reported worldwide, including Japan. As 1 contributor to the increase in cardiovascular risk during the colder months, winter hypertension likely reflects an interaction between environmental factors and human physiological responses. In particular, the prognostically important morning blood pressure (BP) surge is accentuated in winter versus other seasons, as is BP variability. Some individuals may exhibit more marked changes in BP in response to cold exposure, referred to as thermosensitive hypertension. During winter mornings, sympathetic activation due to cold stress and the arousal response overlap, producing a synergistic effect that raises baseline BP, amplifies BP variability, and augments the morning BP surge simultaneously. These mechanisms help explain why cardiovascular event risk peaks during the early morning hours in winter. Approaches to optimizing the living environment and lifestyle during winter to help reduce cold-induced increases in BP are discussed, with a focus on Japan. Incorporation of home BP monitoring and newer approaches, such as digital therapeutics are also important. Overall, winter BP management should consider BP variability, time of day (chronobiology), and the environment, rather than focusing solely on absolute BP levels. The period immediately after awakening represents the most dangerous time window, during which cold exposure, low indoor temperature, awakening-related sympathetic activation, and initiation of physical activity converge. Effective management for individual cardiovascular risk reduction requires a comprehensive approach that optimizes living conditions, lifestyle factors, BP monitoring, and hypertension pharmacotherapy.