Effects of shift work on 24-hour ambulatory blood pressure and its variability among Japanese workers

Objectives This study examined the effects of rotating shift work on blood pressure in a comparison of ambulatory blood pressure and long-term changes in blood pressure between shift and day workers. Methods Ambulatory blood pressure was measured for 24-hour periods at an in terval of 30 minutes for 27 shift workers and 26 day workers when they work ed during the day. Blood pressure was compared between these 2 groups of wo rkers for 4 time categories (awake, sleep, nonwork awake, and work periods) . Their long-term blood pressures, recorded in annual surveys, were reviewe d for long-term changes. These comparisons were adjusted for the effects of body mass index, alcohol intake, anger expression, and physical activity. Results On the average, sleep time was shorter and the anger-in (ie, anger suppressed) score was higher for the shift workers than for the day workers , but body mass index and alcohol intake did not differ between the 2 group s. Even after adjustment for these co-variables, the mean systolic blood pr essure during the 24-hour, awake, and work periods were higher among the sh ift workers than among the day workers. The 24-hour standard deviations of the systolic blood pressures were also higher for the shift workers than fo r the day workers. Among the shift workers, but not among the day workers, a significant long-term increase was observed in systolic blood pressure me asured in the annual surveys. Conclusions These results suggest that shift work may increase systolic blo od pressure levels among Japanese men.