Any PA or Fed regulation for overnight?

I was wondering if there were any Laws in Pennsylvania, or the Federal Government that would state how many people would have to be on duty in a retail store during the "grave yard shift." And if there is, how many should there be? And also, who would i talk to if there were to be an infraction of the law?

You can check this by calling your state office of the Department of Labor, who regulates work hours and conditions.