The goal of this clinical trial is to learn the effect of dexmedetomidine premedication in postoperative negative behavior changes in children compared to midazolam premedication. It will also learn about the effect of dexmedetomidine and midazolam in emergence delirium. The main questions are: * Dose dexmedetomidine lower the incidence of postoperative negative behavior changes compared to midazolam? * Dose dexmedetomidine lower the incidence of emergence delirium compared to midazolam? Researchers will compare dexmedetomidine to midazolam (a common pediatric premedication) to see if dexmedetomidine works to treat postoperative negative behavior change and emergence delirium. Participants will: * Take intranasal dexmedetomidine or oral midazolam or placebo (a look-alike substance that contains no drug) premedication * Fill in the Post hospitalization behavior questionnaire for ambulatory surgery postoperative 1, 3, 7, and 30