Antarctica; extreme environment; 24-hour blood pressure monitoring; Halberg cosinor analysis; blood pressure variability; circadian variability

OBJECTIVE: To evaluate potential changes in arterial blood pressure (ABP) and heart rate (HR) during a 2-month stay in Antarctica, using chronobiological analysis. METHODS: An observational study performed at Mendel research base, Antarctica, during 2011 and 2012. The studied group consisted of 24 participants of the 5th and 6th Czech Antarctic Scientific Expeditions. Three series of 24-hour ABP monitoring were performed, of these two in Antarctica and one in the Czech Republic. Chronobiological analyses of the data were performed (Halberg Chronobiology Center, Minnesota) using population-mean cosinor. The values of MESOR (Midline Estimating Statistic Of Rhythm), double amplitude and the acrophase were obtained for SBP (Systolic Blood Pressure), DBP (Diastolic Blood Pressure) and HR. These rhythm characteristics were compared between the two locations by parameter tests and by the paired t-test.