Are you addicted to the internet?

Tobacco companies, drug cartels and Starbucks beware - the internet may be giving you a run for the money in the addiction department.

According to a study sponsored by Yahoo! and advertising company OMD, internet detox makes people feel emotionally vacant and lost in life. Twenty-eight participants were asked to record their thoughts and feelings during a two-week period of no net usage. From studying the subjects' video and written diaries, researchers noticed that two weeks of internet deprivation affected social lives and left many feeling bored.

Not surprisingly, the study's sponsors said the results provide a good opportunity for marketers.

"It allows a rare glimpse into the reasons consumers make the choices they do and how they are emotionally impacted," said a statement from Wenda Harris Millard, Yahoo!'s chief sales officer. "We can then help marketers apply these insights to reach their target audiences."

Respondents expressed frustration in completing tasks or shopping without the internet. Socially, people found they were unable to maintain relationships with people outside their immediate circle of close friends, since many of them used email or instant messaging programs instead of phones to keep in touch.

In the workplace, the subjects noticed a sharp change in their behaviour as well. Reading the paper and calling friends gave an impression of laziness among their co-workers, in contrast to staring at PCs while surfing news sites and zipping out emails.

In fact, many noticed that the internet gives them cover for doing personal activities while creating the impression that they're working.

"I miss the private space the internet creates for me at work," said "Kim V.," a participant cited in this study.

The study was released in conjunction with Advertising Week in New York City.

Jim Hu writes for CNET News.com