My thirteen year old daughter has to take 40mg(total)daily. She h...

My thirteen year old daughter has to take 40mg(total)daily. She has Down's Syndrome and can't describe her side effects. I've noticed that after about two and a half hours of her taking it, she becomes so drowzy that she will fall asleep anywhere. It knocks her out just like that. In my opinion, it is too strong for her. She becomes this way just from 20mg. This must be some powerful medication!! She slept for about 13 hours after her first dosage. She can't take it before going to school.