I've been on Wellbutrin XL for about four months, for depression not anxiety, and I'm doing great on it. I have a long history of insomnia but even though I take the Wellbutrin at night it is not exacerbating the insomnia problem. My cousin, OTOH, had to switch to taking it in the morning because it was keeping her up at night. So, as dysilap noted, it's definitely an individual thing.