How to explain to friends about depression and chronic fatigue?

I was diagnosed at 16 with bi-polar depression. My fiends also thought that I was just looking for an excuse to miss school and that all it would take is some old-fashioned cheering up. It was hard to explain that I needed to be on medication. What I finally did was find some websites that I felt explained what I was going through the best. Medical sites that explained what bi-polar depression really was. That I wasn't just sad and mad at the world, that I felt this way for no reason other than a chemical imbalance in my brain. That it wasn't my fault. So what I'm saying, is search around on medical sites until you find one that explains it like your doctor would explain it. In such a way that YOU feel it covers everything you want your friends to know, and then show the site to them or give them the URL at school. After that, if they still think the whole thing isn't a big deal and they still think you're just skipping school or being moody, then they aren't really your friends at all. Also, try finding websites with networks that allow you to chat with other people dealing with the same thing and it will help you find the best way to talk about it in real life. I hope this helps, good luck! :)