How active is he? Does he participate in sports or some sort of highly active physical activity of any kind?
Personally I think you are right to resist your MD's recommendation. Most MDs turn too quickly to drugs that mask or alter symptoms. You need to look for causes. The anxiety, anger, depression, and inability to sleep are all part of this. Something systemic is going on. While you might find some "natural" product like melatonin that will also address one or more of his symptoms, to get true & lasting relief you need to address the real cause.