Effects of Diazepam and Ethanol on Heart Rate and Galvanic Skin Responses

: Heart rate (HR), heart rate variability (HRV), and the amplitude and frequency of galvanic skin responses (GSR) were studied in nine healthy young males 2–3 hrs after oral administration of either placebo, diazepam (10 and 20 mg per 70 kg body weight), ethanol (0.78 and 1.22 ml/kg), or combined administration of diazepam (10 mg) and ethanol (0.78 ml/kg). When examinations were performed in resting subjects, ethanol produced significant increases in heart rate, as did combined administration of ethanol and diazepam. Heart rate variability, supposedly correlated to reaction time, was reduced by combined administration of the two drugs. The frequency of the GSR was reduced by both ethanol and 20 mg diazepam, while the amplitude was increased by 10 mg diazepam and reduced by 20 mg diazepam, although not significantly, and was reduced on one occasion by ethanol. Stimulation by mental arithmetic increased all parameters, and more so after drug treatment than after placebo. The results are discussed in relation to the possible effects of diazepam on the autonomic nervous system, and also in relation to the psychophysiological activation theory which presupposes that increased activation is related to increased sympathetic activity. It is concluded that the parameters used are not reliable as indicators of whether a drug is deactivating or not.