As a student working on a Master's in Psychology, I can assure you that schizophrenia (in its many forms) is not anything like when religious people say that God speaks to them or guides them.
As a Christian, I can tell you that seeking God's will in prayer does a lot to change me and the way I think. After much (6 mos.) prayer about a career move, I suddenly had a sense that I shouldn't be considering that career move at all, and instead should be doing something else. Three different people (one atheist friend, one co-worker, and a total stranger) all suggested to me within the same week that I ought to be doing something else with myself. They all three suggested the same career. It was like I'd been blind to the possibility the whole time, until they said it.
After 16 years of climbing the corporate ladder, I walked away from a great job with a great salary to make a lot less money. I'm completely convinced it was God's leading for me to do it. Everything except the money has been better -- quality of life, stress level, family time, etc.
God speaks to me that way a lot, as long as I'm seeking his will for my life. It's almost never that dramatic. Usually it's in the form of a feeling, or an open opportunity, or a sudden desire to get involved in something. There's nothing especially supernatural about it.
I'd even suspect that if you were with me 24 hours a day, you'd suggest that it's nothing, that I'm just responding to my own desires.