The Impact of Work on the Night Blood Pressure Dipping Profile

Objective. The purpose of this study was to elucidate whether ambulatory blood pressure (ABPM) performed during a work day and a non-work day had any impact on the night dipping profile. Study design. A crossover randomized ABPM study in primary healthcare was retrospectively analysed for the occurrence of non-dipping (ND), dipping (D) or extreme (XD) nightly dipping. Non-dippers were defined as subjects with less than 10% and extreme dippers as subjects with more than 20% nightly blood pressure fall measured as mean arterial pressure (MAP). Subjects. Forty treated hypertensives and 40 normotensives (20 men and 20 women in each group), who had performed ABPM twice in a fortnight. They had been randomly allocated to perform a work day or a non-work day as the first period. Result. Only one of the 16 subjects who at any time was a non-dipper remained so during both monitoring periods. Extreme dipping was more often reproduced in nine persons out of 29. Of all 80 subjects, 43.8% (35 persons) remained dippers during both periods. No one changed from a non-dipper to an extreme dipper or the reverse. The odds of being an ND were 3.8 times more common on a non-work day, p=0.010. XDs were slightly more common (1.7 times) on a work day than on a non-work day, p=0.040. There was no correlation as to the degree of MAP and the dipping profile, p=0.629. Conclusions. More subjects were non-dippers at the end than at the beginning of the work week. It is essential to consider this when attempting to identify a non-dipper by ABPM.