Patients aged 18 to 65, ASA status I to III and scheduled to electroconvulsive therapy under general anesthesia every 2 days for 3 to 4 weeks, are included in this prospective observational study. Patients with previously documented adrenocortical insufficiency or under corticosteroid medication are not included Anesthesia protocol is standardized with 0.5 mg/kg propofol, 0.3 mg/kg etomidate and 0.5 mg/kg succinylcholine. Induction of anesthesia is performed after 3 minutes of preoxygenation with 6 l/min fresh gas flow with 100% inspired fraction of oxygen. The patients are maintained in facial mask ventilation until recovery. During the procedure heart rate, non-invasive blood pressure, pulsed oximetry and end tidal carbon dioxyde are monitored.