title: Heart rate variability in male shift workers in automobile manufacturing factories in South Korea.
abstract: OBJECTIVE
  The aim of this study was to determine the effect of circadian rhythm disruption on cardiovascular autonomic regulation by examining potential differences in heart rate variability (HRV) between day- and night-shift workers.
  
  
  METHODS
  The study population consisted of 162 workers who worked both day and night shifts in two automobile manufacturing companies who underwent ambulatory 24-h electrocardiogram recording and completed questionnaires and sleep diaries. Both time and frequency domain indices of HRV were compared.
  
  
  RESULTS
  HRV parameters (mean RR, SDNN, RMSSD, pNN50, TP, HF, LF, LF/HF ratio) reflecting sympathetic and parasympathetic modulation varied less with activity in night-shift workers.
  
  
  CONCLUSIONS
  Circadian rhythm-mediated changes in autonomic regulation of the cardiovascular system were blunted in night-shift workers, which could contribute to an increased risk for cardiovascular disease in overnight workers.
authors.affiliation: , Chuncheon, Republic of Korea.
authors.forename: Sangyoon
authors.initials: S
authors.lastname: Lee
authors.affiliation: , Chuncheon, Republic of Korea.
authors.forename: Ho
authors.initials: H
authors.lastname: Kim
authors.affiliation: , Chuncheon, Republic of Korea.
authors.forename: Dae-Hwan
authors.initials: DH
authors.lastname: Kim
authors.affiliation: , Chuncheon, Republic of Korea.
authors.forename: Myunggul
authors.initials: M
authors.lastname: Yum
authors.affiliation: , Chuncheon, Republic of Korea. sonmia@kangwon.ac.kr.
authors.forename: Mia
authors.initials: M
authors.lastname: Son
mesh_terms: D000328:Adult; D001336:Automobiles; D001341:Autonomic Nervous System / Q000502:physiology; D002320:Cardiovascular Physiological Phenomena; D002940:Circadian Rhythm / Q000502:physiology; D004562:Electrocardiography; D006339:Heart Rate; D006801:Humans; D008297:Male; D066192:Manufacturing Industry; D008499:Medical Records; D056910:Republic of Korea; D012890:Sleep; D011795:Surveys and Questionnaires; D014940:Work Schedule Tolerance / Q000502:physiology*
keywords: Circadian rhythm; Heart rate variability; Night work; Shift work