1. A method for ascertaining the cerebral state of a patient, including a state resulting from the administration of a drug, said method comprising the steps of: (a) obtaining EEG signal data from the patient; (b) obtaining EMG signal data from the patient; (c) analyzing a sample of sequential EEG signal data to obtain a first indication indicative of the cerebral state of the patient; (d) analyzing a sample of sequential EMG signal data temporally related to the EEG signal data sample to obtain a second indication indicative of electromyographic activity in the patient; and (e) producing a composite indication from the first and second indications obtained at steps (c) and (d) indicative of the cerebral state of the patient.