Sex Differences in 24 H Blood Pressure in Night-Shift Workers

Background/Objectives: Gender Medicine addresses how sex- and gender-based differences influence people's health. Blood pressure (BP), which is the leading global risk factor for cardiovascular disease, shows a sexual dimorphism. This is seen also in case of shift work, as shift work is associated with hypertension in the male sex. It is not clear if this may be extended also to night-shift work, as data for this are limited. Based on this background, the aim of this study was to evaluate whether there were sex differences in the 24 h BP profile during a day with a day shift and a day with a night shift. Methods: This study is a post hoc analysis of a previous study where we evaluated ambulatory blood pressure monitoring data for two days, in a day with a day shift (and night of rest) and in a day with a night shift. Results: Overall, 25 subjects (physicians) were included in the analysis, of whom 10 were (40%) males and 15 were (60%) females. No differences were recorded in terms of age, years of work, number of steps, admissions, and calls during the recordings between the two sexes. Subjects worked on average 1.2 night per month, indicating that this population had a low exposure to night-shift work. BP patterns did not differ between sexes, but BP levels were always higher in males than females. Nevertheless, only females showed a significant increase of SBP during the night shift as compared to the night of rest. Both males and females showed a significant reduction in BP dipping during the night shift, but only in females, the significant reduction in BP dipping was maintained after the night-shift work. Interestingly, BMAL1 gene expression, which is a gene of the circadian rhythm, increased significantly after the night shift only in females, suggesting that females display an earlier acrophase than males after night-shift work, which may be associated with tolerance to shiftwork. Conclusions: Our data are consistent with the concept that blood pressure display several sex/gender differences. Males had higher BP values, but females showed signs of lower tolerance to shift work. This might be due to sex differences in the circadian rhythm regulation, which, in turns, regulate physiological functions, such as blood pressure.