I wake up every morning hard as a rock, almost bigger than it feels like I should be. I've never had an issue with getting a hard erection willingly, until recently. I get something, sometimes very hard and sometimes it's hard, then it isn't, then it is, then it isn't.

I'm 35, very healthy and in great physical shape. I take ADD medication (adderrall) but am otherwise on nothing other than a basic one a day viatamin, a vitamin b complex, and glucosomine condrotin. I've been on all of those for years.

Any idea what could cause that?