(CBS/AP) These days we say lots on Twitter. What does the fast-paced forum have to say about us?
Recently, scientists at Cornell University analyzed tweets from 2.4 million people in 84 countries and confirmed that people tend to wake up in a good mood and are happiest on weekends.
Maybe that doesn't sound like big news. But scientists say that in addition to confirming common beliefs about our moods, the study - published in Friday's edition of the journal Science - shows that Twitter can be a powerful research tool.
Overall, the researchers analyzed more than 500 million of the brief, conversation-like exchanges sent over a two-year period. They used a computer program that searched for words suggesting positive mood - happy, enthusiastic, brilliant - or negative mood - sad, anxious, fear.
Exactly what did they find? Unless you're a night owl, a positive attitude peaks in early morning and again near midnight, but starts to dip midmorning before rising again in the evening.
Aha, you might think, going to work and related hassles like traffic explain that pattern. After all, weekends saw more positive tweeting, even though the morning peak of happy tweets occurred two hours later, probably because people slept late.
Not quite. Work-related stress may play a role but can't explain why that same midday dip occurs on the weekend, too, said lead researcher Scott Golder, a Cornell graduate student. Instead, the pattern is likely due to the effects of sleep and humans' 24-hour biological clock, the so-called circadian rhythms that signal when it's time to sleep and to wake, Golder and Cornell sociologist Michael Macy reported.
The researchers also looked at tweets from the United Arab Emirates, where Friday and Saturday are considered the weekend. Sure enough, they saw the same daily pattern (even though the workday begins earlier there than in the West) and the same weekend pattern.
Previous research linked the biological clock and mood but was based mostly on small studies of college students. There are cautions about studying Twitter postings, too: Their authors tend to be younger than the general population, and may be more affluent, better educated and different in yet-to-be-discovered ways.