If being offline makes you feel jittery or anxious, you may have a mental illness. Psychiatrists have decided to list Internet Use Disorder (IUD) as a condition "recommended for further study" in the 2013 edition of the Diagnostic and Statistical Manual of Mental Disorders, or DSM. That means they haven't decided yet whether IUD is a legitimate diagnosis requiring treatment, but might do so in the future.
So, what are the symptoms of this potentially diagnosable mental health problem?
Based on the definition offered by the American Psychiatric Association (the group responsible for the revision of the DSM), IUD is an addiction to Internet gaming. Its symptoms include a preoccupation with gaming, withdrawal symptoms (such as anxiety and irritability) while offline, the need to spend increasing amounts of time gaming (called "tolerance"), loss of other interests and hobbies, inability to limit gaming time, use of gaming to improve mood, deception of family and friends about extent of use, and jeopardizing opportunities because of gaming.
Although IUD is most closely associated with addiction to online gaming, many scientific studies of the condition expand its definition to include excessive Web use in general.
There is some evidence that Internet addiction permanently damages many of the brain regions that are similarly affected by drug or alcohol addiction. In a study published last year, for example, Chinese researchers found reductions in brain volume in 18 young people who were addicted to the Internet compared with the brain volumes of non-addicts. The Internet addicts' diminished brain regions included areas believed to play a role in emotional processing, executive thinking skills, attention and cognitive control. Furthermore, those who had been addicted longer had lower volumes in those brain regions, suggesting a cumulative effect.
Another study published in 2009 found that when online gaming addicts were shown screenshots of the games they used, they exhibited brain activity associated with the feeling of an urge or craving. This is what happens when substance addicts see cues of their drug of choice.
Still, not everyone is convinced that IUD should be classified as a mental health disorder. Some have argued that diagnoses of Internet addiction, like those of shopping addiction, sex addiction and food addiction, are really just symptoms of "the creeping medicalization of everyday life," in the words of Vaughan Bell at Slate. "Almost any problem of excess can now be portrayed as an individual falling foul of a major mental illness," Bell wrote.