I think the burrowing behavior for me is a protective response. You're feeling bad, you don't want others to know or to feel bad also, so you quarentine yourself. This way, your not vulnerable to attack when your not feeling like you can protect yourself and you THINK you are doing good by others by keeping your contagious "feeling bad" sickness away from others.

The problem is of course...you end up avoiding the cure that can help you...and your withdraw leaves others feeling bad anyway.