The Swiss study, reported in the journal Psychosomatic Medicine, point to one potential reason that close relationships -- and marriage, in particular -- have been linked to better health.

To reach the conclusion, researchers from the University of Zurich in Switzerland [Images] studied 51 mostly married German couples for one week, and found those who reported more physical contact, from holding hands to sexual intercourse, had lower levels of the so-called stress hormone, cortisol, in their saliva.

Cortisol is behind several stress-related changes in the body and is secreted in higher levels during the body's fight or flight response to stress.

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The finding found that couples who reported more problems at work had the biggest drop in levels of the hormone through intimacy.

Lead author Dr Beate Ditzen said intimacy was thought to improve hormone levels simply by boosting mood.

She, however, stressed that couples should not race to express more intimacy as such, but rather find things to do together that create positive feelings for both partners.

Intimacy means different things for different couples, Dr Ditzen said.

"This means that there is no specific behaviour that couples should show in everyday life,'' News.com.au quoted her, as saying.

"Rather, all kinds of behaviour which couples themselves would consider intimate...might be beneficial," the expert added.