Fluorescent lights will trigger migraines and tics with me. I have also found out now that gluten triggers tics with me! I saw my homeopath today, the first time since being totally off gluten, and she said that my tics have noticably decreased. I have also found that when I accidentally glutened myself last week, my tics were so much worse for a couple of days.
I also found that I had an easier time sitting still and paying attention in church, without constantly ticcing.
Stress will trigger tics with me as well, as will loud noise (which qualifies as a form of stress with me), and seeing others tic makes me tic as well.
German citizen, married to a Canadian for 28 years, four daughters, one son, eight grandchildren (and one on the way).