Ambien is a controled drug. Usually it depends how long you have been taking it to how long it stays in the system. Most of the time, if you have not taken it for very long, about 2 weeks clean will not show up on drug screen. I use to be a drug screen colector and I have seen up to a month for some drugs and still show up postive for their values.
I wish you the best. Shame the workplace has come to this. Can't even take anything to help you sleep for frear of not getting a job. Now that really sucks.
Carrie