Twitter is an excellent tool for sharing news, keeping up with friends, and a quick laugh, but the platform is also apparently an excellent subject for mood and behavioral studies.

There's just a torrent of new digital media coming into the field, and it's transforming the social sciences, creating new lenses to look at all sorts of behaviors, said Peter Sheridan, a researcher at the University of Vermont.

In a text analysis of 300 million individual tweets from across the U.S., researchers found a number of interesting correlations. For instance, most people sent out happier tweets in the early morning (shortly before 6 a.m.) and late evening (between 9 and 10 p.m. ET). These peaks are consistent across the United States, with the west coast tweeters showing happier tweets consistently three hours behind the east coast. Across the board, people get into their worst moods shortly after midday before rebounding for the end of the day.

Besides the daily variations, researchers also noted several important geographic patterns. For one, Californians, Oregonians, and Washingtonians will be pleased to know that tweets coming from the west coast were consistently happier than those from the east coast. Sun likely has something to do with this elevated mood, because the only east coast state that achieves a comparable level of happiness is Florida, the Sunshine State.

Being out in the sun boosts our mood, improves sleep, and promotes vitamin D production, said James Spencer, a clinical professor of dermatology at Mt. Sinai School of Medicine in New York.

Throughout the course of the week, the study also noted that weekends are much happier than weekdays. The overall tweet mood score peaks on Sunday mornings and dips to its lowest point on Thursday evenings.

The study was conducted by researchers at Harvard Medical School and the Northeastern University College of Computer and Information Scientists, which took into account the location of the tweeter, the time of the tweet, and the general mood of each tweet. Researchers collected 300 million tweets from Sept. 2006 to Aug. 2009.

A new cross-cultural study, performed by sociologists at Cornell University and the journal Science, confirms the Harvard study. Studying tweets from 2.4 million people from 84 different countries between Feb. 2008 and Jan. 2010, researchers similarly discovered that a person's tweets follow emotional patterns throughout the days and weeks, but even through the changing seasons as well, which drives hard at the common assumption that the winter contributes to negative moods.

Both of these Twitter studies align nicely with what we already know about Circadian and mood rhythms, in that these powerful, underlying processes transcend both environment and culture. Circadian rhythms are roughly 24-hour cycles controlled by the presence of the suprachiasmatic nucleus in the brain, which affects physiological and behavioral processes, and is found in most forms of life, from fungi to humans. Previous studies on Circadian rhythm have shown that if you isolate any animal in a sunless room, their sleep and mood rhythms continue as normal.

If you're on Twitter and you have the Google Chrome browser, you can perform a similar mood study of you own. Thanks to a new add-on called ViralHeat, users can now instantly monitor sentiment for Tweets and Twitter search terms.