Is there a regulation on minimum rest hours after drill before you go to work?

Staff, you're looking for a regulation but won't find it because DoD doesn't regulate the commercial sector. Your employer sets your work hours. You should appraise them of your reserve status and schedule and ask for accomodation They either will or won't. However, if they don't AND they've been informed, then the consequences of their position are with them. About the only respite you have is USERRA, BUT you have to had a negative action (firing) because of your Reserve status, BUT you then have to get DoJ to take and interest, BUT DoJ doesn't bite on anything unless it's worth serious dollars (equivalent) or they want to make a policy statement. Hopefully your employer will realize that an employee in butt dragging status for a few hours isn't the most efficient tool in the drawer. The other aspect is how much on-call is actually being activated. If time and circumstance works out to be a few times a year bumping up against Reserves, then neither you or the company have much to talk about. I can't think of the number of times I had to pull double/triple shift equivalents in my tandem career and have no memory of the next weekend because I was catching up on sleep. To a large extent, it's the nature of the beast and doesn't rise to a level where the Government steps into a lose-lose situation.