Thank you for mentioning sleep! I think it’s much more important than people realize. The few times I’ve found myself feeling sick, I go to bed way early, hunker down and sleep 9-10 hours. That’s usually enough to kick it.
I’d say getting enough sleep is a huge preventive for illness. I usually don’t, during the school year, and if the deficit of sleep is too great, I’ll feel under the weather and hit all the stuff in my earlier post so I don’t get sick.
And one you get that tickle in the throat or feel less than 100%, definitely hit the hay like you do and try to get a ton of rest.