Why Sniffing Your Partner's Shirt Helps Reduce Stress

If you're feeling stressed, a whiff of your romantic partner's shirt may help you feel more relaxed, a new study shows.

Researchers from the University of British Columbia (UBC) found that smelling a romantic partner’s clothing was associated with lower levels of the stress hormone cortisol in women's blood, according to the study, published Jan. 3  in the Journal of Personality and Social Psychology.

"Many people wear their partner's shirt or sleep on their partner's side of the bed when their partner is away, but may not realize why they engage in these behaviors," lead study author Marlise Hofer, a graduate student in the UBC Department of Psychology, said in a statement. "Our findings suggest that a partner's scent alone, even without their physical presence, can be a powerful tool to help reduce stress." [11 Tips to Lower Stress]

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The researchers included 96 opposite-sex couples in the study. The men were asked to wear T-shirts for 24 hours, without wearing any deodorant or scented body products. They were also asked to not smoke and to eat only foods that wouldn't affect their body scent. After the T-shirts had been worn for a day, they were frozen to preserve their smells.

Then, the women were given two T-shirts to smell: an unworn T-shirt and one that belonged to either a stranger or the woman's own partner. (In other words, women were either given an unworn T-shirt and their partner's shirt to smell, or an unworn T-shirt and a stranger's shirt to smell.) In both groups, the women were not told whether either shirt was worn, or who wore the shirt.

Women tend to have a better sense of smell than men, which is why they were chosen to be the "smellers" in the study, the researchers said.

After smelling the two shirts, the women participated in a mock job interview and a mental math task; this was done to raise their stress levels. To measure stress, the researchers asked the women questions about how much stress they felt and collected saliva samples to measure cortisol levels, according to the statement.

In the experiment, the women who received a T-shirt worn by their partners, rather than strangers, had lower cortisol levels, the researchers found.

Among the women who received their partner's shirt, plus an unworn shirt, smelling the partners' T-shirts was linked to a significant reduction cortisol levels, compared with smelling the unworn shirts. In addition, the women who smelled their partners' shirts said they felt less stress both before and after the interview and math test, the researchers said.

Furthermore, the effect was greater in women who recognized that the scents belonged to their partners, suggesting the benefits of a loved one's scent are strongest when women know what they are smelling, according to the study.

However, smelling a stranger's T-shirt had the opposite effect: It resulted in higher levels of cortisol throughout the stress test compared with smelling the unworn T-shirt, the researchers said in the statement.

"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," Hofer said in the statement. "This could happen without us being fully aware of it."

The findings could be used to help people cope with stressful situations when they're separated from loved ones, the researchers said.

"With globalization, people are increasingly traveling for work and moving to new cities," senior study author Frances Chen, an assistant professor in the UBC Department of Psychology, said in the statement. "Our research suggests that something as simple as taking an article of clothing that was worn by your loved one could help lower stress levels when you're far from home."

Originally published on Live Science.