How does Provigil stabilize your mood? I am on it as a Mood Stabilizer for my Depression?

I do not know HOW it works as a mood stabilizer, but I do believe it works well as such.
I was given Provigil only for daytime wakefulness (I'm narcoleptic) and I found a pleasant other side-effect was that I felt much better emotionally. I'm not diagnosed with depression but only because I refuse to go to a psychiatrist to BE diagnosed. I'd rather live with my (usually mild) depression than take SSRI meds or any more pills for that matter.
So, yes, it works as a mood stabilizer, and works well for me in that regard. It also does a wonderful job keeping me feeling awake, and I don't want more & more of it. In other words, it doesn't seem to be addictive in a way that I build a tolerance to the amount I take (200mg each morning, or 400mg if I've had a particularly sleepless night).
One word of caution is that when I take 400mg any given morning I have a hard time making simple, normal decisions most of that day.