tourette's syndrome
"Our daughter was on this when she was in elementary school, it was pretty bad. It made her so terribly tired she couldn't keep up in school. Terrible way for a child to live. Over the summer we were going on a vacation and she begged us to take her off it so she wouldn't be so tired so we had to gradually wean her off and then back on again when school started. Thank goodness the tic eventually went away after about a year or a year and a half or so..."