Altered chronome of heart rate variability during span of high magnetic activity

A decrease in heart rate variability (HRV), gauged by the standard deviation, had been associated earlier with exposure to a magnetic storm in space in a transverse study on cosmonauts. A longitudinal study now confirms this result on a clinically healthy man who monitored his ECG for 7 days. The decrease in HRV is documented both in a time-domain and in a frequency-domain measure of HRV, and is found to affect frequencies lower than one cycle in about 3.6 sec, pointing to an underlying physiological mechanism other than the parasympathetic as being putatively responsible for the physiological response to changes in magnetic activity. In the search for mechanisms, new invasive and non-invasive hardware-software systems offer themselves to assess long-term and short-term hemodynamic changes.