they probably will show up on a Substance Abuse Panel -- 10 (SAP- 10) screen if your school is testing for drugs for sports team. but as far as them being used to enhance your ability in a sport, i highly doubt that to be the case. you might have to provide a prescription for taking the pills, but if you can't provide a prescription, that might indicate drug abuse... but i wouldn't worry about it too much. i dont' know about canada though...
Yes, sleeping pills can show up as drug abuse on a test. As Fitzy said, I would state that you are taking them and provide a written prescription.
They will ask you to list any and all OTC(over the counter) meds/drugs that you have taken for the last week. I list the sleeping pills and when they ask how many I tell them...enough to go to sleep ( and for me thats waaaaaay more then most people) but never give an exact number. I've had drug test for week many times and they have never said any thing about my sleeping pills habit.
My borther takes melatonin...but it's because he's autistic, and if he doesn't then his heart beats too fast for him to sleep or some shite...not really sure, but I know they load him up with pills -_-