"There's an adrenaline high that people who use technology constantly get from trying to balance the BlackBerry, the cell phone … trying to keep all these balls in the air at the same time," author Bryan Robertson said.

To make time for the gadgets, some users will "give up time with family," Rutgers University School of Business Gayle Porter said. "They'll give up getting together with friends. They'll give up taking care of themselves, getting enough sleep - things like that."

She's researching a paper that will argue that businesses could be sued by employees who feel they were encouraged or even forced to stay connected 24 hours a day and then developed an addiction to their gadget.

The trends are clear, the dangers incontrovertible. Uncontrolled use of Blackberry-type devices can lead to physical, mental and social debilitation. Someone is bound to announce the development of a new 12 step program for Crackberry addicts. The road to recovery will begin with the assertion that "I am an addict." Meanwhile, employers should develop comprehensive written warnings to accompany the provision of any PDAs. These guidelines should set clear parameters for appropriate Blackberry use. With half the marriages in this country already ending in divorce, employers need to avoid any possible inference that work - and work-provided equipment - is a significant cause of marital discord. In the ever-expanding definition of risk management, this is one area where increased vigilance - and a few disclaimers - are definitely in order.

Tanning, dermatologists have found, makes the skin give off endorphins. These opioid compounds make a person feel good. They are the reason endurance runners report "runner's high." Could there really be such a thing as tanner's high?

The author of the 2005 report suggesting that frequent tanning may be a type of substance abuse is Richard Wagner Jr., MD, deputy chairman of dermatology and director of dermatologic surgery at the University of Texas Medical Branch at Galveston. Wagner says the idea came from skin cancer patients who couldn't stop tanning.

"Every dermatologist will tell you there are some patients we are concerned about," Wagner tells WebMD. "We know ultraviolet (UV) light can lead to skin cancer. Yet we all see patients with skin cancer who are always tan. We tell them not to tan on purpose, and some say, 'But doc, I like it too much. It makes me feel relaxed. I know I am getting skin cancer, but I can't stop.'"

So Wagner went down to the beach and gave addiction questionnaires to people who were sunning themselves. As many as half met the psychological criteria for substance-related disorder. That substance: sun tanning.

However Colin Drummond, professor of addiction psychiatry at St George's Hospital Medical School, London, said: "I have concerns about calling everything in the world an addiction."

"There's a tendency to translate extremes of behaviour into addictions."

Professor Drummond said addictions meant a particular chemical mechanism occurred in the brain which determined a person's behaviour.

Such a mechanism had not yet been established for sunbathing, so the habit could not be labelled an addiction.

He said people tanned because they wanted to conform socially, not because they were addicted to the feeling.