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J Occup Health year 2001 volume 43 number 1 page 32 - 38
Classification Original
Title 24-Hour Heart Rate Variability in Shift Workers: Impact of Shift Schedule
Author Ludovic G.P.M. van AMELSVOORT1, 2, Evert G. SCHOUTEN2, Arie C. MAAN3, Kees A. SWENNE4 and Frans J. KOK2
Organization 1Department of Epidemiology, Maastricht University, 2Division of Human Nutrition and Epidemiology, Wageningen University, 3Foundation for ECG analysis, University Hospital, Leiden, 4Department of Cardiology, University Hospital, Leiden, The Netherlands
Keywords Shift work, Work schedules, Heart rate variability
Correspondence L.G.P.M. van Amelsvoort, Department of Epidemiology, Maastricht University, P.O. Box 616, 6200 MD, Maastricht, The Netherlands
Abstract 24-Hour Heart Rate Variability in Shift Workers: Impact of Shift Schedule: L.G.P.M. van AMELSVOORT, et al. Department of Epidemiology, Maastricht University-Disturbance of the circadian pattern of cardiac autonomic control by working at night when the physiological system anticipates rest could explain part of the elevated cardiovascular risk in shift workers. Analysis of Heart Rate Variability (HRV) is a non-invasive tool to estimate disturbances of the cardiac autonomic control. To assess the influence of working at night on cardiac autonomic control, HRV levels were determined in shift workers. 24-h ECG recordings were made during a day on morning shift and a day on night shift. Within person differences between a morning and a night shift were calculated. Possible modification of the reported effects by the shift schedule was determined. Significantly elevated mean %LF during sleep was found on a day worked on night shift compared with a day on day shift (%LF + 3.04, P<0.01). Type of shift schedule was found to be a significant modifier of this effect. The difference in %LF between the night and day shift for the different shift schedules apart were: + 0.88% for the workers in the fast forward rotating shift, + 3.06% for the fast backward rotating shift, + 6.15% (P<0.001) for the medium speed backward rotating shift and + 1.18% for the shift workers without a regular shift schedule. The results suggest an increased sympathetic dominance during a night shift sleep, indicating an inferior sleep quality. Optimisation of this schedule might diminish this impact and could contribute to a reduction of the cardiovascular disease risk among shift workers.