Can being a vegetaran affect a drugs test?

Ok pardon my ignorance on the matter but I heard that a reduced creatine level can affect drug test results and being a vegetarian i guess my creatine levels should be low. I don't really know if I should believe this or not so I said I'd ask the good ladies and gentlemen of the answers community. Also I'm on sleeping pills at the moment but clearly they don't work, even taking two, its 5:50 here at the moment. Would they affect the test? I was sure that drug test would account for a person being on legal drugs but a friend said otherwise and well damn you paranoia!!