It’s great to do things you enjoy. But can you go too far with a hobby? And at what point does it become an addiction? That’s the question experts are trying to answer about playing video games.

Even though gaming has been around for almost 50 years, studies about its harms are still in the early stages. Different groups have come to different conclusions about whether problem playing should be called an addiction.

The World Health Organization added “gaming disorder” to the 2018 version of its medical reference book, International Classification of Diseases. But the American Psychiatry Association’s manual, the DSM-5, didn’t. (So far, gambling is the only “activity” listed as a possible addiction.)