Smelling a partner's scent from clothing may help reduce stress levels, a new psychological study finds. However, smelling a stranger's clothing results in opposite effect.

Smelling A Partner's Scent May Help Reduce Stress

In the new study, researchers at the University of British Columbia in Canada attempted to examine the psychological effects of smelling t-shirts that were worn by romantic partners or strangers.

The researchers took in 96 opposite-sex couples and instructed the male participants among them to wear a clean t-shirt each for 24 hours without putting on any perfumes or deodorants.

The researchers also told the male participants to not smoke and consume foods that would otherwise alter the scent of their bodies. After the 24-hour period, the researchers then froze the worn t-shirts in order to preserve their scent.

Then, the researchers gave two t-shirts each to the female participants to smell. One of the t-shirts either belonged to a partner or to a stranger and the other one was not worn. The researchers did not inform the women about which t-shirts they were giving them.

Also, they selected women as their main subjects in the study because they have the tendency to have a stronger sense of smell than men.

Stress Test

The researchers later instructed the women to undergo a stress test that included a mock job interview, a math task, and also answer questions related to their stress levels.

The women also provided the researchers with saliva samples in order to calculate the levels of their cortisol.

The Results

According to the results of the study, the researchers found that women who smelled their partner's t-shirt felt calmer and less stressed before and after they underwent the stress test.

In other words, they found that smelling a partner's clothing was related to lower levels of the stress hormone known as cortisol in women's blood.

They also found that the women who smelled their partner's t-shirt and managed to recognize the familiar smell also had lower levels of cortisol. According to the researchers, this suggests that the benefits of smelling a partner's scent are much more effective when women know what they are smelling.

A Stranger's Scent Produces The Opposite Effect

Smelling a stranger's scent, on the other hand, had left the female participants with higher levels of cortisol throughout the stress test, the researchers discovered.

This could be related to how humans fear strangers especially strange men, said Marlise Hofer, who is the lead author of the study and a graduate student at the University of British Columbia's department of psychology.

The research was published on Jan. 3 in the Journal of Personality and Social Psychology.