Wellbutrin is one of the most stimulating antidepressants. Of course results vary by the individual, but this drug isn't usually used if anxiety is a major problem because of this unless the anxiety is caused by depression. Because it's so stimulating it can also cause insomnia. Zoloft can be stimulating to some, as antidepressants in general are pretty odd to take, or it can be sedating. When to take it usually doesn't matter much if you're taking it once a day. It is possible to divide doses into two to minimize side effects like sedation. This is something you should discuss with your psychiatrist, particularly as he or she is now adding up the drugs you're taking and therefore adding up the side effects as well, and also duplicating some of the effect on neurotransmitters, which can also be a problem. I'd discuss what you're experiencing with your psychiatrist and also ask, if wellbutrin is causing you problems which are typical of the drug, why not taper off of it and just see if the Zoloft works for you? Perhaps the wellbutrin is working really well for the depression, there are probably reasons, but it's good for you to know what you're getting into and if the psychiatrist understands what he or she is doing -- often, they really don't, so it's good to be reassured. You can also ask at that time given what you're feeling when the best time to take the drug is.