Infradian cardiovascular rhythms during a 520-day simulated journey to Mars (Mars500 project)

DANIEL E. VIGO; MARIANO SCARAMAL; RAFAEL BAPTISTA; FRANCIS TUERLINCKX; EVGENY BERSENEV; OMER VAN DEN BERGH; ANDRÉ AUBERT

Simposio; XIII Latin American Symposium on Chronobiology (LASC); 2015

Introduction: Although physiological infradian rhythms have been described in humans, no evidence was found about the occurrence of seasonal rhythms under strict controlled situations. Objective: Taking advantage of the Mars 500 study, where six subjects were confined during 520 days while simulating a Mars journey, we sought to explore infradian systolic and diastolic blood pressure (SBP, DBP) and heart rate (HR) rhythms. Methods: SBP, DBP, and HR were assessed each morning and evening on a daily basis. A Lomb-periodogram was applied to each signal. Results: Significant infradian rhythms were found for mostly all variables, but with different periods. Remarkably, all subjects showed a similar evening HR rhythm with a period of 198 ± 10 days, and an amplitude of 31 ± 11 bpm2 (p < 0.001). The rhythms seemed to be phase synchronized during the second third of the journey. Conclusions: Evening HR presented infradian periodicity in Mars500 crew. Several factors may account for these findings, including seasonal changes in mood, physical activity, nutrition or sleep along confinement.