Researchers examine the wake-up times of German Twitter users

For many people, the alarm clock rings much too early on Mondays. These people suffer from a mismatch between their social obligations and natural human circadian rhythms that are dictated by the biological clock, which is normally set by the sun. Chronobiologists call the difference in mid sleep time on work and free days "social jetlag". Researchers at the University of Potsdam and the GFZ German Research Centre for Geosciences recently studied whether posts on social media can be used as a new data source for understanding sleep and wake activity.

In an extensive study, they investigated wake up times of German speaking Twitter users. For a full year, the researchers collected all tweets containing "Guten Morgen", the German phrase for good morning. The result was 1.5 million tweets sent by more than 200,000 users. The researchers then analyzed the differences between when the phrase occurred on week days and weekend days, and how this changed over the course of the year. "In the months when the days are short, wake times on Sundays are closely related to the time of sunrise" said the lead author of the study, Tatjana Scheffler from the Department of Linguistics at the University of Potsdam. "But the observed relationship breaks down the week that daylight savings time comes into effect." These results confirm those obtained earlier from survey-based sleep studies.

The researchers presented their study last week at the 10th International AAAI Conference on Web and Social Media (ICWSM) in Cologne, Germany.