The daily dynamics of heart rate variability in women engaged in regular work schedules versus shift-workers
Aim. A comparative analysis of the daily dynamics of heart rate variability in women: shift-workers vs. working only during the daytime. Material and methods. The study was performed among medical staff women of Tyumen. Participants represented 2 groups: group of shift-workers engaged in nocturnal working regimen with no sleep allowed and group engaged in daytime time work only. Two middle-age periods were considered: average age: younger than 36 years, age group I (shift workers: 29.9 ± 4.1, daytime workers: 29.5 ± 4.2; and 36-54 years, age group II (shift workers: 44.6 ± 5.0; daytime workers: 46.7 ± 6.1 years. The study of heart rate variability was carried out 4 times during activity phase: at 08, 12, 16, 20 hours. Results. The average daily values of heart rate, systolic / diastolic blood pressure (SBP/DBP), Q-T, P-Q, QRS did not differ significantly in women of middle age engaged in regular daytime vs. shift-work regimen. In shift-workers, there was a significant decrease in the average daily values of heart rate variability (SDNN, RMSSD, pNN50%, CV%,%VLF,% HF) in the background (supine) recordings and with an active orthostatic test in comparison with the values in daytime workers. According to 2-way ANOVA, shift-work caused the remodeling of the diurnal patterns of the following variables: SBP,%LF (orthostatic), interval Q-T (background), RMSSD (background),%VLF (orthostatic), HF% (background),%VLF (orthostatic) by comparison to the patterns of daytime working women. Conclusions. The results of 2-way ANOVA allowed to determine the hours when comparative assessment of heart rate variability between shift-working and daytime-working women revealed significant differences between 2 groups (morning hours: at 8:00 - for the interval Q-T, RMSSD and%HF in the supine position and daytime hours, at 16:00 - for%LF and%VLF in the orthostatic test).