I don't know about you, but I don't find this very surprising. I feel a lot more like a tortise than a hare before I've had my first dose of caffeine for the day. But I generally get into a higher gear right after that, and my mood becomes a whole lot better too.
It's hard to deny the mood-enhancing effects of caffeine when you look at the stock price of a company like Starbucks. According to Wikipedia,
By the time of its initial public offering on the stock market in 1992, Starbucks had grown to 165 outlets. In April 2003, Starbucks added nearly that many new outlets in a single day by completing the purchase of Seattle's Best Coffee and Torrefazione Italia from AFC Enterprises, bringing the total number of Starbucks-operated locations worldwide to more than 6,400.
The company probably wouldn't have enjoyed such success, even at the prices they charge, if they didn't make a whole lot of people feel good.
But psychologists can reproduce the effect in the lab, without any chemical additives:
Study explores 'manic' thinking
How fast thinking makes us happy, energized and self-confident
Fast thinking, or "racing thoughts," is most commonly known as a symptom of the clinical psychiatric disorder of mania (and of the manic part of bipolar disorder or "manic-depression"). But, according to Princeton University psychologist Emily Pronin, most healthy people also have experienced racing thoughts at some point in time--perhaps when they are excited about a new idea they have just learned, or when they are brainstorming with a group of people, or even when they lie in bed unable to fall asleep. Pronin and her Harvard colleague Daniel Wegner decided to explore whether inducing people to think fast might lead them to feel some of the other experiences also associated with the manic experience.
It would be most intresting to know a lot more about the neurochemistry involved here. No doubt it's related to "runner's high", endorphins, higher levels of epinephrine (which is closely related to the neurotransmitter norepinephrine), and that sort of thing.
At all events, in times like these, it's always good to have some happy news.