Sleep and sickness

Twice in my life I’ve been up for longer than 60 hours straight–once on the Crucible during basic training, and now when I had a three-day straight lan party. After both events, I became exceptionally sick. I had assumed that the Crucible sickness came from sleeping outside and in the rain, but this second time I was never outside.
So, now that the background information is out of the way, why is it that whenever I have a serious sleep defeciency, I get amazingly sick? Does a lack of sleep waken the immune system?

Request for clarification: when did the sleeping outside in the rain part come in?
After you’d been up for longer than 60 hours straight?

I obviously meant <i>weaken</i> not <i>waken</i>.

Er, poor phrasing on my part.
During the Crucible, I was able to nap for about half an hour the first night–it was one of those “lay down and toss and turn and get up for firewatch 10 minutes later” deals. I laid under my poncho and liner until I got kicked up for firewatch.

I think sleep deprivation over a period of time does weaken the immune system. I am not sure about the length of time this takes. There could be other factors as well… stress, fatigue, poor nutrition.

The effect is still the same. You didn’t get any meaningful sleep for a long period of time. And I don’t know that extended periods out in the elements when you’re asleep is any worse for the health than extended periods when you’re awake.