Each and every time I go through something difficult in my life my guitar is there.  Even when other people are not available it has been there through the most tough times I can think of.  It relaxes me the moment I pick it up.  I highly reccomend playing guitar to friends who are stuck in a depression or filled with anger.  A couple of them are still playing many years later.  I remember a friend going through a bitter divorce.  He was soooo very angry.  Every day that I saw him I would hear him complain about the latest thing she did to him or what she had taken from him.  This was a long drawn out procedure.  I drove him to the guitar store and asked him “Why don’t you put all that anger into learning how to play one of these?” He looked around and started with the excuses.  I picked one up and plugged it into the loudest amp I could find ignoring him at the moment.  I cranked that thing up (much to the dismay of the store personnell) and began to just jam.  He was tuned out.  Finally he shut up and said OK I get the point.  Grinning at him when he finally got the picture.  That was close to thirty years ago and he still plays bass today.  The instrument enables your brain to focus on something other than your problems and makes them seem so far away for a while.  Often I have been distracted long enough that a problems solution has come to me while jamming.  I can’t reccommend it enough.  Here is an article on this very topic.  I hope you enjoy it.