Influence of smoking and gender on diurnal variations of heart rate reactivity in humans

We evaluated the influence of smoking and gender on diurnal variations of h eart rate reactivity during performance of two vigilance tasks (auditory an d visual) and a working memory task. Heart rate was measured hourly (08:00- 21:00 h) at rest and during performance tasks in 20 smokers (ten men, ten w omen) and 20 non-smokers (ten men, ten women). Smoking and gender influence d reactivity only at certain times, especially at the earliest and latest h ours and during the post-lunch period. Smokers displayed major post-lunch i nterference and a pattern of lowered stress in the second half of the day. Women showed greater reactivity at the first daily recording, although thei r levels later became similar to the men's and were even lower. The stateme nt that women are myocardial hyperreactors must be further investigated, as it seems women may take longer than men to adapt to a task. (C) 2001 Elsev ier Science Ireland Ltd. All rights reserved.