Doc gave me a 2 week trial of Cymbalta, I took it for 12 days before switching. During that time I was seriously sleeping 12 hours+ and waking up tired feeling like a zombie. The day I stopped Cymbalta the tiredness went away.
Now I'm taking 50mg Zoloft, and I'm back to my old self with Insomnia...
How long have you been taking the Zoloft bc it can take 2 wks—one doctor even told me a month—before it even starts working? So, if you haven't been taking it very long, and you normally have insomnia, maybe it's not the Zoloft at all. My pharmacy actually stuck a drowsiness warning on my last bottle, but drugs can certainly affect ppl differently. I dont really notice any side effects. Other than that quite possibly unhelpful suggestion, all I can say is ask your doc or pharmacist.