More than one in eight U.S. adults finds it hard to stay away from the Internet for several days at a time and about one in 11 tries to hide his or her online habit, according to a study released on Tuesday.

The study by researchers from the Stanford University School of Medicine in California found one in 8 adults admitted they needed to spend less time online, saying this showed "problematic Internet use" is present in a sizable portion of the population.

"We often focus on how wonderful the Internet is — how simple and efficient it can make things," said Elias Aboujaoude, the study's lead author, in a statement.

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"But we need to consider the fact that it creates real problems for a subset of people."

The study involved a nationwide telephone survey of 2,581 respondents in the spring and summer of 2004 with researchers then examining the data and preparing the report which appears in the October issue of CNS Spectrums: The International Journal of Neuropsychiatric Medicine.

The survey found that 68.9 percent of respondents were regular Internet users and 13.7 percent found it hard to stay offline for several days at a time.

It found 12.4 percent often stayed online longer than intended, more than 12 percent said they saw a need to cut back on their Internet use, and 8.7 percent tried to conceal "non-essential" Internet use from family, friends and employers.

A smaller number, 8.2 percent, said they use the Internet to escape problems or a bad mood, while 5.9 percent felt their relationships suffered because of excessive Internet use.

Aboujaoude said the results do not show that people are suffering from a clinical disorder, and he added that more research must be done to make any such determination.

The study comes after several reports over the past decade concluded that Internet and computer use can be addictive, including habits such as visiting pornography Web sites to compulsive videogame play.

One report published earlier this year in the journal Perspectives in Psychiatric Care said that the Internet may promote addictive behaviors and pseudo-intimate relationships like "cybersex."

That study said that 5 percent to 10 percent of the population likely will experience Internet addiction.

It said signs include a disregard for health or appearance, sleep deprivation and decreased physical activity and social interaction with others, as well as dry eyes, carpal tunnel syndrome and repetitive motion injuries of hands and fingers.

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