title: Geomagnetic disturbance associated with decrease in heart rate variability in a subarctic area.
abstract: BACKGROUND
  Physical environmental variables, such as the natural variation in the geomagnetic field in and around the earth, influence biological processes and human health. The effect of geomagnetic disturbances on heart rate variability (HRV) in healthy students in a subarctic area is studied herein.
  
  
  METHODS
  Seven-day records by Holter ECG were obtained from eight clinically healthy subjects in Alta, Norway (70 N). Frequency- and time-domain measures of HRV were compared between 24-hour spans of high geomagnetic disturbance versus quiet conditions.
  
  
  RESULTS
  A 5.9% increase in the 24-hour average of HR (P = 0.020) and a 25.2% decrease in HRV (P = 0.002) were documented on days of high geomagnetic disturbance. The decrease in spectral power was found primarily at frequencies lower than 0.04 Hz and was not statistically significant around 3.6 sec.
  
  
  CONCLUSIONS
  The physiological mechanism involved may be other than the parasympathetic, usually identified with spectral power centered around 3.6 sec, a spectral region wherein no statistically significant differences were found.
authors.affiliation: Department of Medicine, Tokyo Women's Medical University, Daini Hospital, Nishiogu, Japan. frtotk99@ba2.so-net.ne.jp
authors.forename: K
authors.initials: K
authors.lastname: Otsuka
authors.forename: G
authors.initials: G
authors.lastname: Cornélissen
authors.forename: A
authors.initials: A
authors.lastname: Weydahl
authors.forename: B
authors.initials: B
authors.lastname: Holmeslet
authors.forename: T L
authors.initials: TL
authors.lastname: Hansen
authors.forename: M
authors.initials: M
authors.lastname: Shinagawa
authors.forename: Y
authors.initials: Y
authors.lastname: Kubo
authors.forename: Y
authors.initials: Y
authors.lastname: Nishimura
authors.forename: K
authors.initials: K
authors.lastname: Omori
authors.forename: S
authors.initials: S
authors.lastname: Yano
authors.forename: F
authors.initials: F
authors.lastname: Halberg
mesh_terms: D000328:Adult; D001110:Arctic Regions; D004562:Electrocardiography; D015716:Electrocardiography, Ambulatory; D004574:Electromagnetic Fields; D004777:Environment; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged