2. Chronobiology Laboratories, University of Minnesota, Minneapolis, Minnesota
3. Finnmark University College, Alta, Norway
4. Auroral Observatory, University of Tromso, Tromso, Norway
Key words: geomagnetic activity, heart rate variability, graded response, magnetoreception, chronoastrobiology, subarctic area,
Running Title: Graded response of HRV to geomagnetic.
Summary :
Background: It is becoming recognized that geomagnetic activity may influence biological processes, including the incidence of various human diseases. There is evidence that heart rate variability (HRV) may serve not only as an index of autonomic coordination of the circulation, but also as a powerful predictor of risk in apparently healthy subjects. This study focuses on any effect of geomagnetic disturbance on HRV, by comparing different indices of HRV of young, healthy men living in a subarctic area on days of low (ap; 0-7), middle (ap; 7-20), and high (ap; 20-45) geomagnetic activity.? Subjects and Methods: The effect of geomagnetic disturbance on HRV is examined herein on the basis of 7-day records by Holter ECG, obtained longitudinally on 5 clinically healthy men, 21-31 years of age, in Alta, Norway (70 degree N). Frequency- and time-domain measures of HRV were analyzed for each subject on separate 24-hour spans.? Results: A graded alteration of HRV endpoints was found in association with increased geomagnetic activity. As time-domain measures of HRV, SDNNIDX and the 90% length of the Lorenz plot decreased statistically significantly on days with increased geomagnetic disturbance (p=0.0144 and p=0.0102, respectively). A graded decrease in frequency-domain HRV measures was also validated statistically for the total spectral power (decrease of 18.1% and 31.6% on days when 7
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