I've never heard of any connection between the two...

I can personally tell you that I *had* been taking melatonin fairly regularly for sleep problems for the past couple years, and yet I *still* came down with EP anyway. In fact, I had been taking it even more religiously than usual for the last few months before it happened because I'd been having so much more trouble sleeping ever since my mom passed away.

I think stress has a lot more to do with it than anything. It weakens your immune system more than most people realize, regardless of how much sleep you're getting...