From the emotional nostalgia that certain smells can evoke to some odd recent research suggesting weight gain could be connected to smelling food, our olfactory system plays a part in some remarkable neurological functions. Now a new study from researchers at the University of British Columbia has revealed that the scent of a person's partner can tangibly reduce feelings of stress and literally lower levels of the stress hormone cortisol.

This new study took 86 opposite sex couples and tasked the men with "scenting" a clean t-shirt for 24 hours. The women were chosen as the "smellers" for no reason other than the fact they tend to have better senses of smell than men.

The women were then given one of three t-shirts to smell: a clean one, a shirt that was worn by a stranger, or one that had been worn by their partner. Immediately after smelling the shirt the women were subjected to several stress tests, including a mock job interview and a math task. They also supplied saliva samples to track their cortisol levels.

The results showed that smelling a partner's t-shirt reduced subjective feelings of stress and measurable cortisol levels. Plus, if the person correctly identified their partner's smell this increased the stress-reduction effects.

Perhaps most interesting was the discovery that smelling a stranger's scent actually increased a woman's cortisol levels, possibly revealing a strange evolutionary tic that people may have developed to protect ourselves from danger.

"From a young age, humans fear strangers, especially strange males, so it is possible that a strange male scent triggers the 'fight or flight' response that leads to elevated cortisol," says lead author on the study, Marlise Hofer. "This could happen without us being fully aware of it."

A pragmatic outcome of the research is the suggestion that when loved ones are apart, stress levels can be legitimately reduced by actions such as taking an item of clothing from a partner to sniff. This research involved t-shirts in particular, but the scientific revelation could certainly be applied to other pieces of clothing.

The study was published in the Journal of Personality and Social Psychology.