Evidence from a chronobiometric approach that chronic smokers, although normotensive, show an increase in diurnal blood pressure

To investigate the effects of chronic smoking on the 24 h blood pressure and heart rate pattern in normotensive subjects.

Twenty-five smokers and 25 age-, weight- and height-matched non-smokers, who were all clinically healthy young men, gave their informed consent to undergo non-invasive, automated, ambulatory blood pressure monitoring for 24 h. The smokers in this study consumed on average 25.4 cigarettes per day. The lifestyle of the two groups was comparable because they worked as clerks at the same company. The 24 h blood pressure and heart rate data were analysed according to chronobiological methods.

Smokers were found to show a statistically significantly higher blood pressure versus non-smokers by day but not by night. Furthermore, smokers showed a slight increase in the mean level of circadian blood pressure rhythm versus non-smokers, accompanied by an amplification of one cyclic component of this periodicity.

The increase in diumal blood pressure in smokers might be regarded as the haemodynamic effect of chronic smoking in normotensive subjects. Such an effect seems to be substantiated pathophysiologically by an amplitude overmodulation of one of the harmonic components which confer the circadian blood pressure rhythmicity. Because the diumal increase in blood pressure persists for two-thirds of the day-night period, one can argue that this phenomenon in normotensive smokers might be a premonitory sign of future hypertension. Apart from this, one can hypothesize that the diumal increase in blood pressure might itself be a cause of target organ damage, given its consistent within-day duration and daily repetition.