Football star David Beckham has said that he plays with Lego pieces to control stress. Comedienne Ellen DeGeneres playfully pranks her television guests.

While serving as Britain's prime minister, Mr David Cameron was known to play video game Angry Birds at the end of a long day.

The importance of play for children is well documented. Researchers are now turning their attention to its benefits for adults.

What they are finding is that play is not just about goofing off. It can also be an important means of reducing stress and contributing to overall well-being.

Play is easy to recognise in children and animals - for example, an impromptu game of tag or chase. But what does it look like in adults?

How adults play is "as unique to an individual as a fingerprint" and could mean collecting stamps, tossing a football, reading a book or climbing Mount Everest, said psychiatrist Stuart Brown, founder of the National Institute for Play in Carmel Valley, California. He said: "What all play has in common is that it offers a sense of engagement and pleasure, takes the player out of a sense of time and place, and the experience of doing it is more important than the outcome."

Researchers said that humans are all wired by evolution to play.

Psychology research professor Peter Gray of Boston College said: "Play primarily evolved to teach children all kinds of skills. Its extension into adulthood may have helped to build cooperation and sharing among hunter-gatherers beyond the level that would naturally exist in a dominance-seeking species."

In other words, for our earliest ancestors, play was not just about having fun, it may have been a way of keeping the peace, which was critical for survival.

There is a reason that adult play exists in modern society, said Professor Lynn Barnett of the department of recreation, sports and tourism at the University of Illinois. One theory is that play is therapeutic and there is research to back that up, she said.

"At work, play has been found to speed up learning, enhance productivity and increase job satisfaction. And at home, playing together, such as going to a concert or movie, can enhance bonding and communication."

Prof Barnett said that playful adults have the ability to transform everyday situations, even stressful ones, into something entertaining.

She co-authored a study that found highly playful young adults - those who rated themselves high on personality characteristics such as being spontaneous or energetic, or open to "clowning around"- reported less stress in their lives and possessed better coping skills. "Highly playful adults feel the same stressors as anyone else but they appear to experience and react to them differently, allowing stressors to roll off more easily than those who are less playful."

PLAY COMES IN DIFFERENT FORMS

Being a playful adult may also make us more attractive to the opposite sex, according to a study from Pennsylvania State University.

Researchers there asked 250 students to rate 16 characteristics that they might look for in a long-term mate. "Sense of humour" came in first among the males and second among the females.

"Fun-loving" came in third for both and being "playful" placed fourth for women and fifth for men.

Lead researcher Garry Chick speculates that the attraction to playfulness may be rooted in evolution. "In men, playfulness signals non-aggressiveness, meaning they would be less likely to harm a mate or an offspring," he said. "In wo- men, it signals youth and fertility."

Not all adults play alike. In a study published in April in the journal Personality And Individual Differences, researchers examined the complexities of adult playfulness in an effort to tease out patterns of behaviour. They identified four types of playful adults:

• Those who outwardly enjoy fooling around with friends, colleagues, relatives and acquaintances

• Those who are lighthearted and not preoccupied by the future consequences of their behaviour

• Those who play with thoughts and ideas

• Those who are whimsical, showing interest in unusual things and are amused by small, everyday observations.

Lead researcher Rene Proyer, a professor of psychology at Martin Luther University Halle-Wittenberg in Germany, said that by showing how varied playfulness can be, he hopes people will be encouraged to become more playfully engaged with others.

Prof Brown said: "Play is a basic human need and is as essential to our well-being as sleep. When we're low on play, our minds and bodies notice."

Over time, he added, play deprivation can reveal itself in certain patterns of behaviour - we might get cranky, rigid, feel stuck in a rut or feel victimised by life.

To benefit most from the rejuvenating benefits of play, he said, one needs to incorporate it into everyday life, "not just wait for that two-week vacation every year".

Ms Brittany Rouille, 28, a travel blogger based in Oregon, said she made a point of incorporating more play into her life a few years ago after her stressful lifestyle left her depressed.

"It wasn't until I reintroduced play into my life that I started to feel like myself again," she said. "Now I play every day, whether it's roller- blading, painting or playing my harmonica, even if it's for an hour."

THE WASHINGTON POST