Noise and hypotension - potential association and moderation

Health effects studies of noise have exclusively focused on hypertension or blood pressure increases as outcomes. This strong focus was very plausible as the stimulation of the sympathetic system by loud sounds as a typical response towards an external stressor was well supported. Secondly, hypertension is the major risk factor for cerebro-vascular disease and mortality. Nevertheless, early experimental studies did not show only increases in blood pressure but also recorded no response or decreases of blood pressure. Due to the narrowed focus on increases in blood pressure the results were analyzed and reported only with respect to blood pressure increases and the distribution of the observed effects in the whole sample were not shown. Only some German studies reported also the percentage of respondents with decreases in blood pressure. One larger institutional report even presented the overall response matrix of the participants in an Annex. We took up on this evidence and included questions on self-reported hypotension into 2 of our surveys and recently published two articles showing a potential and moderated relation of hypotension with traffic sound exposure. We present a summary of the results obtained in the two studies, discuss potential pathophysiological pathways and conclude what consequences this association may have in general for the investigation of sound – blood pressure relationships in epidemiological studies.