How do you support your immune system?

I work nights, so getting a full 7 to 8 hours of sleep per 24 hour period is troublesome for me. I have started to eat fresh oranges on a daily basis for the vitamin C content. I figure it's a cheap, healthy way to obtain nutrients that will boost my immune system.

So far I've been able to fight off all the respiratory stuff this year---it was the norovirus that got me. Hopefully that's all the sickness I'll have to deal with......I usually get bronchitis and maybe a cold or two each year and would much rather suffer through those than a GI illness, so Mother Nature owes me one!

What's weird is, even with all of the stress I went through during 2012 I only got sick once, and that was the bronchitis I came down with just before New Year's. Nothing else. I swear, I must've run through most of the cold viruses when I was younger, because I very rarely get them now and they tend to be gone within a few days. It's when the bronchitis hits me that things get dangerous, because usually I'll progress to either pneumonia or a REALLY bad asthma exacerbation if I don't get antibiotics and prednisone within a day or two of onset.

I'm not sure as to what I owe this relative resistance to infection, but I do take special care with my sleep hygiene, plus I get a yen for things like oranges and V-8 juice around this time of year.....guess that Vitamin C really does help after all.