engleski

Comparison of heart rate variability during a day and night shift

Parameters of heart rate variability (HRV) may provide a useful non-invasive tool in studying the physiological effects of work-related stressors, such as shiftwork. To assess the effects of shiftwork on some cardiac activity parameters during a day and night shift, three healthy middle-aged nurses, participated in the investigation, whose R-R intervals were continuously recorded during the afternoon (14.00-21.00) and night (21.00-07.00) shifts. Results showed significantly higher mean values of R-R intervals (lower heart rate) at night shift, when compared to the afternoon shift. This was probably due to lower workload level during night shift and the effects of normal circadian rhythm. Similarly, standard deviations of R-R intervals (Sd) also showed some differences in work effort and/or circadian effects between these two shifts. Similar pattern of changes in the mean R-R intervals and their Sd during working at night shift and sleeping at night, also suggested the effects of the circadian rhythm on cardiac activity in night shift. Spectral analyses of the data on hour-to-hour periods, when power of spectral densities at different frequency bands (low and high frequency) were expressed in normalised units, seem to have reflected parasympathetic modulation of HRV during the night shift. This effect was significantly smaller during the afternoon shift, which seems to be logical, since parasympathetic activity is more prominent during night, than afternoon period. Generally speaking, the comparison of HRV during day and night shifts indicated that, apart from the differences in workload, circadian rhythms (time of day) have significant influence on changes in cardiac activity.

heart rate variability; working shift

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