title: Circadian rhythms as a basis for work organization: a study with live line electricians.
abstract: OBJECTIVE
  With the assumption that circadian rhythms influence human performance, the work of live line electricians was reorganized and evaluated. The hypothesis was that in highly physical and attention-demanding work, the organization of tasks, according to the ideal period of day and day of week, should diminish stress and consequent work risks.
  
  
  BACKGROUND
  There are only a few studies reporting the work of electricians and even fewer approaching work organization. Moreover, these investigations often do not consider human physiological limitations and capabilities as well as task demands.
  
  
  METHODS
  A new work system was proposed with consideration of (a) the circadian cycles and homeostatic processes; (b) the effect of heat, which is a zeitgeber (synchronizer) for the biological clocks; and (c) the degree of physical and mental demands of the different performed tasks, which was assessed on the basis of opinions of the electricians and physiological markers of stress that are controlled by circadian rhythms. The traditional and new systems were compared on the basis of two cognitive indices (the arrangement of matchsticks and the perception of a minute) and three physiological markers of mental-to-physical loads (heart frequency and the level of adrenaline and noradrenaline).
  
  
  RESULTS
  Both physical and mental loads were reduced in the new system.
  
  
  CONCLUSIONS
  Work organization should include consideration of human circadian rhythms, mainly when stressful and high-risk tasks are involved.
  
  
  CONCLUSIONS
  The findings can be applied in any work design, but they are especially suited for highly demanding work carried out outdoors.
authors.affiliation: Graduate Program in Industrial Engineering, Federal University of Rio Grande do Sul, Av. Osvaldo Aranha, 99, 5o andar, Porto Alegre, RS 90035-190, Brazil. liabmg@gmail.com
authors.forename: Lia Buarque de Macedo
authors.initials: LB
authors.lastname: Guimarães
authors.forename: Jose Luis Duarte
authors.initials: JL
authors.lastname: Ribeiro
authors.forename: Tarcísio Abreu
authors.initials: TA
authors.lastname: Saurin
authors.forename: Paulo Ivo Homem
authors.initials: PI
authors.lastname: de Bittencourt Júnior
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001288:Attention; D002940:Circadian Rhythm / Q000502:physiology*; D006804:Ergonomics; D006801:Humans; D008297:Male; D008875:Middle Aged; D010561:Personnel Staffing and Scheduling / Q000458:organization & administration* / Q000592:standards; D011210:Power Plants; D013312:Stress, Physiological; D013315:Stress, Psychological / Q000503:physiopathology / Q000517:prevention & control*; D014887:Weather; D014940:Work Schedule Tolerance