A recent research study released by sociologists at Cornell University showed that people's moods followed a similar pattern not only through a single day but also through the week and the changing seasons.

Drawing data from messages on the social media site Twitter, posted by its more than two million subscribers in 84 countries and with different timezones, researchers learned that regardless how bad-tempered one was upon waking up, the person manages to cheer up by breakfast. Later in the afternoon, probably because energies have been spent in work or at school, a person's moods slow down, before perking up again near bedtime.

The new analysis suggests that moods are driven in part by a shared underlying biological rhythm that transcends culture and environment, according to the New York Times.

The study's authors, Scott A. Golder and Michael W. Macy gathered up to 400 messages from each of 2.4 million Twitter users written in English, from February 2008 through January 2010.

Of those that they worked on, they discovered that about 7 percent qualified as "night owls," whose moods or upbeat-sounding messages peaked around midnight and beyond. Morning people accounted for 16 percent, who showed mood peaks very early in the day.

The researchers established that for the average user in each country, positive posts began around breakfast time, from 6 a.m. to 9 a.m.; falling gradually until between 3 p.m. and 4 p.m., then going upward again, rising sharply after dinner.

Weekend patterns shifted about two hours later, with the morning peak closer to 9 a.m. and the evening past 9 p.m. The researchers speculated most likely the reasons were because people sleep in and stay up later.

"This is a significant finding because one explanation out there for the pattern was just that people hate going to work," Mr. Golder was quoted as saying on the New York Times. "But if that were the case, the pattern should be different on the weekends, and it's not. That suggests that something more fundamental is driving this - that it's due to biological or circadian factors."