Surfing the internet randomly and using file-sharing programs may be a sign of depression, say researchers at Missouri University of Science and Technology.
"The study is believed to be the first that uses actual internet data, collected unobtrusively and anonymously, to associate internet usage with signs of depression," says assistant professor of computer science Dr Sriram Chellappan.
The team collected a month's worth of internet data - anonymously - for 216 students from the campus IT department. They were tested for signs of depression, using the Center for Epidemiologic Studies-Depression (CES-D) scale.
And the team found that depressed students tended to use file-sharing services, send email and chat online more than the other students. They also tended to use the high-bandwidth applications often associated with online videos and games, more than the others.
Students who showed signs of depression also tended to use the internet in a more random manner, frequently switching among applications. Chellappan thinks this may indicate trouble concentrating, a characteristic associated with depression.
The randomness was revealed by an examination of the 'flow duration entropy' of students' online usage. This describes the consistency of internet use during certain periods of time.
"Students showing signs of depression had high flow duration entropy, which means that the duration of internet flows of these students is highly inconsistent," says Chellappan.