When are we the happiest? (visualization)
According to a three year observation and data mining project made by Northeastern University and Harvard University, people of the U.S. are most happy in the morning and the evening. This of course is inferred by people who use Twitter.
The data was calculated using over 300 million tweets (Sep 2006 - Aug 2009). You can figure out your own interpretation of the data, but I would guess during the day when everyone is at work is when we are the most unhappy and before and after work we are at our happiest.