+1 on the seeing a doctor comments if it's seriously regular insomnia. Oddly enough, based on my limited knowledge of sleep disorders, I often hear of regular exercise being a common prescription for people w/ sleep disorders. A good bike commute is just that... regular exercise.

As for your other questions, I ride in all weather. I don't have studs yet so excessively icy conditions force me onto metro, but otherwise I just ride regardless.

I ride through minor illness too. If I'm too sick to ride, I'm too sick to be at work.

I've been bikeless for almost two weeks. My life is way more boring w/o my bike commute. It takes a lot to keep me from it. Thank goodness I'll be building up my new bike this weekend and back in the saddle next week.