What are the symptoms of internet addiction?

See DSM: Essentially, when instead of the pleasure it becomes problematic. The person is preoccupied with the habit; spends more and more time on internet; without computer , is irritable, unhappy; time with computer instead of other responsibilities; there is no control over the habit; cont to do it despite consequences. I treat it with "physiological extinction".

Any addiction: Is hallmarked by a persistent, compulsive use of a "substance" despite negative consequences. In this case, negative consequences could be ignoring responsibilities, loss of a social life or even ignoring the basic things we all need such as adequate sleep, good nutrition and adequate exercise.