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Work in the night shifts breaks down natural biorhythms, leading to the development of desynchronosis, a decrease in melatonin synthesis, a violation of autonomic regulation, arterial hypertension, obesity, insulin resistance, immune system dysfunction and the development of tumor pathology. However, quantitative indicators of cardiovascular system adaptation to work at night shifts, the neuro-emotional strain caused by labor intensity, gender peculiarities of the cardiovascular system, and, generally speaking, physiological cost of the work, remain insufficiently studied.
The heart rate variability (HRV) analysis as well as comprehensive analysis of 6-leads ECG was performed in doctors (men (n=7) and women (n=9)) and nurses (women (n=18)) at the beginning and the end of daily duty was done with the help of cloud analytical platform Cardiolyse . The correlation analysis, using both linear and rank correlation was used.
It was found that in male doctors the intensity of the shift load (the number of night shifts per month, NNSM) positively correlated with the shift of autonomic balance LF/HF towards sympathicotonia. Female physicians showed a positive correlation of NNSM with the increase in the absolute and partial activity of the subcortical sympathetic nerve centers (VLF, VLFn), index of activation of the subcortical nerve centers (VLF/HF), the centralization index [IC =(VLF+LF)/HF)], total HRV (measured by SDNN), autonomic circuit activity (parasympathetic modulation) (RMSSD, pNN20).At the same time, the nurses’ (female) experience of working in night shifts was positively correlated with an increase in the specific activity of the barorereflex center of the medulla oblongata [LFn(%)=LF*100/(VLF+LF+HF)].
Moreover, many ECG parameters shown significant correlation with NNSM in both male and female groups, for example ST shift, P-wave amplitude, sum amplitude of QRS-complex etc.
The obtained results indicate, firstly, the gender difference in the mechanisms of adaptation to work in night shifts. Secondly, in women doctors, unlike women nurses, there is a greater number of reliable correlation between the intensity of the load of night shifts and shifts of vegetative homeostasis, which can be regarded as the specific features of adaptation to more strained doctors’ work, compared with nursing work.