I started last Thursday, so I've completed one week now. If I'm having any side effects at all, they are very minor. I have had some insomnia, but I hadn't really thought of it as being anything of significance until reading this thread just now. Maybe, I guess. There's no way to know.
I started on riluzole June 3rd, and haven't notice any obvious side effects related to that either. At times I feel that my fatigue is getting worse since I started it, but then again, of course it is.
-- Steve