"Sufferers spend unhealthy amounts of time playing online games, viewing p 0 r n o g r a p h y or emailing."
In my case, rarely.
However, I know I'm addicted. Several reasons. Too hot outside. Nothing on TV. Nothing in the house to read. Drama in the Health Forums . Take my time with on-line newspapers, e-magazines and don't get my hands dirty on a newsprint. Stock market. Commodity Futures market. Youtube.
The internet is the largest library in the world, however chaotic. It is addictive for academians as well as the 3 listed above.