It starts with forts, those boyhood bastions of male exclusivity. Eventually it evolves into sports-trophy-laden studies, basements and even retreat rooms claimed from garage space.

Men's dens - private male spaces - are where men sequester themselves to work, rest, de-stress, indulge in hobbies and just plain ponder. And unlike women, men tend to crave their own sanctum for relaxation and introspection."Men are simply less social creatures," Frank Dattilio, a University of Pennsylvania psychologist, tells Men's Health magazine in its April issue.

"A woman will call a friend if she has a problem; a man will go and sit on the back porch. It's all part of the stoicism we've come to think of as being masculine."

Another reason for the popularity of privacy for men may be their increasingly disparate roles.

"The pressures on a man come from many different directions today," says Asher Jason, a therapist. "They're expected to be cold-blooded as providers but also warm and sensitive as husbands and fathers. I think their need for privacy is a response to this."