I just started taking cymbalta. This will be my second week on it. I started on 30mg for one week and moved to 60mg about 5 days ago. It is helping to ease the pain of my fibromyalgia and my anxiety is under control. How ever it is making me really tired. I have no motivation at all. I sleep alot. After I take it in the morning I want to go back to sleep. How long will this last?