People who send excessive texts and e-mails may have a mental illness, according to an article in a leading psychiatric journal.

As more people leave the office computer, only to log on as soon as they get home, the American Journal of Psychiatry has found addiction to text messaging and emailing could be another form of mental illness.

The article, by Dr. Jerald Block, said there were four symptoms: suffering from feelings of withdrawal when a computer cannot be accessed; an increased need for better equipment; need for more time to use it; and experiencing the negative repercussions of their addiction.

Block said that although text messaging was not directly linked to the Internet, it was a form of instant messaging and needed to be included among the criteria.

"The chief reasons I see to consider it are motor vehicle accidents that are caused by cell phone instant messaging, stalking and harassment via instant messaging, and instant messaging at social, educational, (and) work functions where it creates problems," he said. "It should be a pervasive and problematic pattern, though, not isolated incidents."

Block said addiction to e-mail and texting is better documented in Asian countries such as South Korea, where a number of studies have been published on Internet addiction, than in the U.S. where little research has been done.

Click here to see Block's full article.