The World Health Organization (WHO) keeps track of diseases and conditions on a global scale. They are currently updating their International Classification of Diseases (ICD) and will be recognizing a new disorder: Gaming Disorder. It involves mostly young adults and teenagers who have a severe addiction to online or onscreen gaming. It calls the disorder one that is the result of "addictive behaviors."
While many teens and young adults enjoy gaming and sometimes go at it for hours, for it to rise to the level of a disorder, the players must have lost control of either how long they spend playing or how intensely they involve themselves in the game world. There is plenty of research that supports gaming disorder as a legit issue; however, some experts believe that the gaming behaviors of hours of play and an inability to stop or slow down play are symptoms of some other problem like depression or anxiety. The issue is hard to define because some gaming behavior can be excessive, but isn't a true addiction. The number of people whose gaming habits impair their ability to function well is likely much smaller than some would believe.