I have tried Nuvigil twice now - once at 150 mg daily, more recently at 50 mg daily, and both times I've had to stop because of the depression that I notice around 3 weeks into it. Eventually I become an emotional wreck, sobbing at the slightest thing and feeling detached and kind of vacant. I won't say that it did nothing to help my focus, but any improvement was definitely not significant enough to outweigh the depression.