The effect of high ambient temperature on the adjustment of operators to fast rotating 12-hour shiftwork.

Abstract

The aim of the investigation was to study the effect of high ambient temperature (HAT) on the adjustment to fast rotating 12-h shifts by following the time-of-day variations of certain circadian and stress indicators. We investigated 12 male HAT operators and 21 individuals working in normal ambient temperature (NAT) in a thermoelectric power plant. The shift system of both groups comprised an 8-day cycle of 2 shifts per day (day shift: 0700 to 1900; night shift: 1900 to 0700), with 2 successive days of the same shift followed by 2 days off. We followed variations in oral temperature, 11-oxycorticoids, as well as catecholamines adrenaline and noradrenaline excretion at 4-h intervals during 2 day and 2 night shifts. Our data show daily oriented circadian rhythms of operators working on fast rotating 12-h shifts in conditions of HAT and NAT. Reduced general activation was observed in the second half of the prolonged 12-h night shifts, more pronounced in HAT operators. The stress indicators investigated here showed a stress reaction in HAT operators at the beginning of the first day shift. Both prolonged 12-h shifts and high ambient temperature impose extra demands and may have an impact on the performance and work safety of the operators.