Twitter usage largely mirrors daily work schedules and school calendars, an analysis of data on the social networking site from the US shows.
The data reflects the amount of "social jet lag" caused when social demands make people wake up much earlier than their biological rhythms would prefer, said researchers from the University of Chicago in the US.
The study, published in the journal Current Biology, analysed the Twitter activity of more than 246,000 users from 2012 to 2013 to look for daily patterns of usage.
The tweets were tagged with geographic location data from more than 1,500 counties in all 50 states and the District of Columbia.
The data serve as a proxy for people's sleep and wake times, a public record of sorts that shows when someone is awake and still using Twitter.
Across the US, there is a daily slowdown in tweets at night when most people go to bed.
The researchers saw that this nighttime lull shifts to later times on weekends relative to weekdays, a phenomenon they call "Twitter social jet lag."