The purpose of this study is to determine the effect of a single dose of Lorazepam on salivary cortisol in children undergoing digestive endoscopy. To do so, the patients will be randomized in three groups. The first group receives the Lorazepam, the second group receives a placebo and the last group receives no intervention. Each patient will have three saliva samples taken at three different time point on the day of the endoscopy and will be asked to fill out questionnaires on anxiety and overall satisfaction of the procedure.