According to research done by Jennifer Lerner of Harvard, those who are in a sad mood tend to more money.

How did she test the theory? Test subjects were shown a sad video about the death of a boy's mentor. Once the movie was over, the subjects were asked to buy bottled water. Those who watched the emotional movie were willing to spend four times more on the water than those who did not watch the movie at all. However, the subjects said the video had no effect on their spending habits.

Lerner said this test is different from the idea of retail therapy--where people buy items at a store to cheer themselves up. Lerner says, "People have no idea this is going on."