I don't think depriving yourself of sleep will have any effect on your UA the following day, I'm no expert but I can't imagine it would increase your chances enough to worry about it. Get a good night's rest. I took fiber up until the day of my UA. Fiber directs the thc metabolites to your feces so it can't hurt. The only advice I have consistently seen is to stop exercising 2-3 days prior to your UA, get lazy and increase fatty food intake.