Did you know: You can use Facebook to track your friends' sleep

A software developer in Denmark has created a way to track the sleep patterns of his Facebook friends using only the activity data available on the social network. The tool, developed by Søren Louv-Jansen, is based on the activity timestamps that Facebook stores on users of its site and Messenger app. Because many people check Facebook in the morning and before they go to bed at night, Louv-Jansen was able to piece together information on their sleeping habits (though it only works for frequent users).

Louv-Jansen has published the source code for his tool on GitHub, and explained how it works it in a Medium post last week. Using the software to check Facebook's database on user activity every ten minutes, he created graphics depicting his friends' sleep patterns, and discovered some broad trends, as well. His friends' sleep was largely regular throughout the work week, for example, and more erratic on the weekend.