I used to get sick or have allergies flare up everytime the weather changed.

In November I started eating raw vegetables and fruit everyday. Work has a cafeteria and I get a salad. At home I have mostly organic.

I haven't been sick or had bad allergies since.

As far as being exhausted, yes. I generally ride close to 100 miles on the weekend and my work commute is 34 miles round trip, so I am slowly building up. It doesn't help that I get home at 9PM on Monday and Wednesday nites, driving a car. But it just takes time to build up. But yeah, I'm not one to sacrifice sleep to ride my bike, but I do feel tons better anytime I ride my bike even if I don't get all the sleep I need.