Is there such a thing as a "mental health leave of absence"?

The environmental stress of my workplace is effecting my life. I need time away from the situation in order to address these issues, and a mere week's vacation is definitely not enough time to heal and make important decisions about how to best handle my options. I feel too beaten down to stand up for myself, and I can't regain self-confidence while I'm daily/nightly submerged in this mentally/emotionally abusive environment. I know I'm supposed to go to the "supervisor" with these problems, but the culprit IS the big boss...he plays mind games...my blood pressure is at a very dangerous level...but I'm too weak to know the right way to handle it. Please don't suggest I file harassment charges (though he deserves it), he's too good at turning things back around.