IMPACT OF SHIFT WORK AND RACE ETHNICITY ON THE DIURNAL RHYTHM OF BLOOD-PRESSURE AND CATECHOLAMINES/

To evaluate the effects of shift work and race/ethnicity on the diurna l rhythm of blood pressure and urinary catecholamine excretion of heal thy female nurses, 37 African American women and 62 women of other rac es underwent ambulatory blood pressure monitor and urine collection fo r 24 hours that included a full work shift: day shift (n=61), evening shift (n=11), and night shift (n=27). Awake and sleep times were evalu ated from subjects' diaries. Of African Americans, 79% who were workin g evenings or nights and 32% working day shifts were nondippers (<10% drop in systolic pressure during sleep), whereas only 29% of others wo rking evening+night and 8% working day shifts were nondippers, Regress ion analyses indicated that evening+night shift workers had a 5.4 mm H g (P<0.001) smaller drop than day shift workers, and African Americans had a 4.0 mm Hg (P<0.01) smaller drop than others. The odds of an eve ning+night shift worker being a nondipper were 6.1 times that of a day shift worker (P<0.001), and the odds of an African American were 7.1 times that of others (P<0.001). Total sleep time was significantly gre ater in the non-African American day shift workers than in the other 3 groups. After controlling for work shift and race/ethnicity, we deter mined that longer sleep times predicted less dipping (absolute and rel ative) in blood pressure. Urinary norepinephrine and epinephrine were higher during work than nonwork in both racial groups of day shift wor kers, but in evening+night shift workers the difference was small and in the opposite direction. These results indicate that being African A merican and working evening or night shifts are independent predictors of nondipper status. Higher sleep blood pressure may contribute to th e known adverse effects of shift work.