The invention relates to a method and an apparatus for monitoring the autonomous nervous system of a sedated patient. According to the method, skin conductance is measured through a time interval. Average skin conductance values and the number of fluctuation peaks are in the interval are calculated and analyzed, and an indication is given of the state of pain/discomfort in the patient as well as the state of awakening in the patient. The invention is particularly applicable for use with anaesthetized or artificially ventilated patents, as separate output signals are automatically provided, indicating the need for analgesics and hypnotics, respectively.