Chronomics of heart rate variability on earth and in space.

Chronomes are time structures consisting of multifrequency rhythms, elements of chaos, and trends in chaotic and rhythmic endpoints. Chronomics maps the dynamics of organisms' broad interactions with the environment near and far, rather than merely the daily routines. We introduced the chronomics of heart rate variability (HRV), characterized by a broad time structure, that includes the prominent circadians and also ultradian (notably about 8h and about 12h) and infradian (notably about-weekly, about-yearly, and about 10-yearly) changes, in addition to undergoing trends with aging. Alterations in these HRV chronomes are known to predict the presence of disease in the near future. Thus, for the health and safety of astronauts, HRV chronomes should be assessed before, during and after the mission in the International Space Station to check for any alteration. Future work should focus on how phenomena in the cosmos, including helio- and geomagnetics, can affect physiological chronomes, those of the HRV in particular.