As per the study conducted by researchers, overall happiness is declining in US. Peter Dodds, the author of this study, collected several words written in tweets.

Researchers used Mechanical Turk, software from Amazon, and hired several volunteers also to give rating to the sense of happiness of Americans.

For instance, laughter was given a score of 8.5, greed 3.0, terrorist 1.3 and so on.

Researchers revealed that the pattern to use words on twitter changed over time. This study was published in PLoS ONE.

It was found that Valentine’s Day and Christmas were high points whereas low points were given to tsunami in Japan, economic depression in US.

“All the most negative days are shocks from outside people’s routines,” Dodds said in a statement. “But the overall happiness signal is on the decline.”