People worldwide wake up happy, get grumpier as the workday drags on, but then reach a second wind of euphoria by day's end, researchers said Thursday, despite differing cultures and religions.

Researchers used posts from Twitter, the popular networking and microblogging site, to gauge global mood swings and found that regardless of culture or geography, moods followed similar patterns, including an expected increase in happiness on weekends.

Researchers have known for some time that people can share similar mood rhythms during the day, but those studies typically depended on observing small and similar groups, the researchers said.

We realized that previous small-subject-pool studies' results were inconclusive, and there was an opportunity for us to make a contribution, Scott Golder, graduate student in sociology at Cornell University, wrote to IB Times in an email. Previous studies used small, homogeneous subject pools, typically using U.S. undergraduates. Our subject population is over two million, and includes people from 84 countries around the world. The researchers examined 509 million tweets over a two-year span.

With tweets in hand, Golder and his advisor Michael Macy, Cornell professor of sociology, put the millions of words into a text analysis program, the Linguistic Inquiry and Word Count, which allowed them to see how many times users posted words associated with positive or negative thoughts.

The duo published their findings in Thursday's online issue of Science.

The researchers used words that fit into two categories: positive and negative.

In the positive pile: words like agree, awesome, definitely, fine, fondly, outgoing, paradise, pleasing, pretty, special, sunny, thanks, fantastic, humor, reward, super, virtue, Golder wrote. Among the negative bunch sulked the words, aching, afraid, cynic, fear, fury, mad, raging, sad, ticked, war, abandon, enemy, panic, remorse, vulnerable.

By determining the frequency of the positive or negative words, the researchers could gauge the mood of the Twitter users.

When contacted online, Twitter communication officials declined to comment on the study Thursday, citing the high volume of requests they receive.

We believe that social media represents an enormous opportunity for social scientists, Golder wrote. Though social scientists will likely always study people using well-established techniques like laboratory experiments, interviews and surveys, the ability to passively observe the behavior of millions of people on the internet is a powerful new tool for the social sciences.

Other linguists and social scientists have picked up on Twitter as a research tool.

For example, researchers at Carnegie Mellon University in Pittsburgh, Penn. found that regional dialects such as the Southern y'all made the transition to the online world in tweets.

Tim Grant, a forensic linguist at Aston University in Birmingham, UK, studies how to give attribution to Twitter posts that could help in criminal investigations.

Ben Zimmer, executive producer of the Visual Thesaurus and Vocabulary.com and the former On Language columnist for The New York Times, called the study an interesting one, and part of a new wave of work that takes a data-driven approach to analyzing affect and emotional expression, in an email to IB Times. Linguists themselves may be a bit wary of this brute-force word-counting approach, but the results can be striking, with robust correlations.

Personally, I'm excited by all the new research possibilities that are made possible by the Twitter corpus and other collections of online texts. Granted, the results of this particular study might not seem so earth-shattering -- the conclusions that 'people get crankier as the day goes on' and 'people are happier on weekends' would strike many as self-evident, Zimmer wrote. But I think we're on the cusp of a new era of looking at language and communication.... We're learning more and more about the linguistic signatures that we leave behind, and what these traces say about our own personalities and the ways we interact.

The Cornell researchers are also releasing a web site (http://timeu.se) that will allow the public to explore the rhythms of each other's days. We realized that, as interesting as these rhythms are to us for their scientific value, people are curious about their social worlds and interested in the lives of others, Golder wrote. This tool allows people to see for themselves what millions of others are doing, and when.

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