WASHINGTON — When someone calls Julie Eyerman at work, Brad Mislow may be in the background, commenting on the conversation. And why not? They work together every day, and have for eight years, at a major advertising firm in New York.

In fact, they have become so much a part of the other's life that even though they are both married to other people, they call each other their work spouse.

You may share a cubicle or office with him. You may realize she finishes your sentences. You argue, you make up, you share confidences. You have inside jokes, you support each other, and you know the other one's real spouse's birthday.

This sort of work relationship has become so much a part of our lives that it has become part of our jargon. It has even been studied by the Gallup Organization. Conclusion: Work spouses (the platonic kind) increase productivity and heighten morale.

The seeds of Eyerman and Mislow's "marriage" were planted almost a decade ago in graduate school for advertising. Mislow is a copy writer, and Eyerman is an art director. Eight years ago, they were hired as a team. Now, they're seen as one unit. BradandJulie.

They even fight like spouses. They see the same frustration, same facial tics. "You take on the real characteristics of a couple," Mislow said. "But there's not the baggage of the married stuff."

Could it be that this happens because we're spending more time at work? Is it because we see our co-workers for more hours than we do our families? Or is it simply that the nature of the work force has changed, and we're much more social and relaxed than workers of yore?

One answer may lie in the changing demographics of the work force.

As a new generation of employees is entering the workplace, it is changing the way we work. Younger workers are looking for a network of friends at the office more than ever before, according to a survey of 2,000 workers by SelectMinds, a corporate social-networking company.

Nearly half of the younger employees surveyed said the availability of support or networking programs for employees with common interests was a very important factor in their decision to join and remain with an employer, compared with 36 percent of their older peers.

The closeness that Mislow and Eyerman share might also stem from a survival sort of instinct, Mislow said. "We've been through bad economic times and good ones. We have meals together. We travel together. We're in strange hotel rooms."

"But different rooms!" Eyerman interjected.

And it's well documented that having a friend at work, or a work spouse, is good not only for morale.

"Having a work spouse is not only a good thing, but it might be a prerequisite for good work," said Tom Rath, global practice leader for the workplace with the Gallup Organization. Having such a relationship means you'll be seven times more likely to be engaged at work, Gallup studies have shown.

"There is always the potential that people will get too close in the workplace, that things will get romantic and go awry," Rath said. "But our research would indicate potential risks don't outweigh the benefits" of having a work friend or work spouse.