Patients are monitored before induction of anesthesia. Propofol is started on the randomized infusion rate. Sufentanil bolus are given according to randomization. BIS level is followed. Time to reach BIS < 50 is monitored. BIS after 30, 60 and 90 minutes are registered. Lowest BIS during surgery are registered. Total amounts of sufentanil and propofol recorded.