It's not addictive. In fact I found myself not wanting to take it after a while because I had so much energy from getting good sleep, I wanted to stay up late doing stuff. (Even though I should, so I get to sleep at a decent hour.)

I recommended 1mg per 50lbs of body weight, and get the fast acting one, not the slow-dissolving one; those made me drowsy the next morning.

It is a little harder to snap to attention right after waking up, but I shake that off quickly; probably a sign I slept well.

It does affect everyone differently though. I haven't had any negative effects myself, other than with the slow-dissolving "long-lasting" pills (but some might need that to stay asleep).