People’s moods follow fairly predictable rhythms based on time of day and season of the year, according to the results of a study of Twitter users.

The study, conducted by the Department of Sociology at Cornell University and published today in the Science magazine, identified individual-level diurnal and seasonal mood rhythms in cultures across the globe. The data was gather from millions of public Twitter messages.

The researchers found that individuals awaken in a good mood that deteriorates as the day progresses, which is consistent with the effects of sleep and circadian rhythm. People’s moods tend to improve again in the evening.

They also found that seasonal change in baseline positive affect varies with change in daylength.

People are happier on weekends, but the morning peak in positive affect is delayed by two hours, which suggests that people awaken later on weekends.

The study drew on messages posted by more than 2-million people in 84 countries, and found that people around the world have similar mood patterns through the day and across the seasons.