Twenty-four-hour monitoring of heart rate, motor activity and smoking behavior including comparisons between smokers and nonsmokers.

The present study was an attempt to monitor continuously and in parallel cigarette consumption, heart rate, and physical activity under field conditions. In a first experiment the test-retest reliability of the recording devices was evaluated with a small number of nonsmoking students on days with similar schedules. The intraday development of heart rate and activity revealed a remarkable intraindividual stability, and the test-retest reliability coefficients calculated between the totals of heart rate and activity revealed values of 0.73 and higher for heart rate and 0.47 and higher for activity on comparable days. The second experiment was done with housewives as subjects to see whether heart rate and/or activity might differentiate smokers from nonsmokers in subjects who are less strictly bound to a fixed daily work program. The smoker/nonsmoker comparisons revealed significantly higher heart rates for smokers but almost identical activity readings. In a third experiment it was tested whether partial smoking abstinence in the morning might differentiate the morning and afternoon heart rates in smokers. Heart rate but not activity was significantly decreased during the abstinence period. Taken together, the simultaneous monitoring of heart rate and activity might be a valuable instrument in smoking research, since it is sensitive enough to detect manipulations of the smoking behavior under natural conditions.