Women likelier to be addicted to Facebook than men, say researchers.
Psychologists from the University of Bergen in Norway have also designed a chart of symptoms signalling whether someone has an unhealthy devotion to social networking.
They studied 423 students for signs of addictive behaviour in the way they used and felt about Facebook.
They found that some participants showed clear signs of "Facebook addiction" similar to those exhibited by people addicted to drugs, alcohol and other chemical substances.
Younger people were more likely to become addicted to Facebook than older people and women were at greater risk than men, the researchers said.
People who suffered from anxiety or social insecurity were heavier users of the website, most likely because they found it easier to use the technology than to communicate with people in person, they added.
The study also found that extroverted people were more likely to be addicted to Facebook, while people who were well organised and ambitious were less at risk, using the website primarily for work or networking purposes.
The findings were measured using the "Bergen Facebook Addiction Scale", a new list of six criteria for each of which a person is given a score from one ("very rarely") to five ("very often").
Categories include feeling an urge to use Facebook an increasing amount, trying and failing to limit your use of the website, and feeling unsettled if you are denied access to your account.
The study described that scoring "often" or "very often" on at least four of the criteria suggests you may be addicted to Facebook.
The finding has been published in the Psychological Reports journal.