Coffee

What is it about coffee that draws me in? I started my coffee habit after my daughter was born (just like mom said I would!). It started as a way to calm the extreme anger I had in the mornings and throughout the day. It helped my depression on those dark winter days and perked me up when I just wanted to crawl back in bed. Well...after I found out I was pregnant a third time, I continued to drink my one cup a day that you are "allowed." However, I realized after a process of elimination that the coffee was making my morning/afternoon/evening sickness ever worse. So, I stopped. This was the first of March. Just last week I had another cup on a day when I was so tired and worn out I didn't think I could stay awake to drive to church, much less teach VBS and then drive home! WOW!! I'd forgotten how much better I felt with that wonderful goodness in my system! :) My husband had been frustrated with my attitude in the mornings, but I haven't received any complaints in the last week since I started drinking coffee again.
Here's my question:
What is it about the coffee that makes me feel this way? It can't be the caffeine, b/c I was drinking a soda in it's place and that didn't do it for me. Is there something else in coffee that picks me up and puts me in a better mood?
How do you feel about coffee?