The scent of the male partner helps women stay calm. Conversely, being exposed to a stranger's scent has the opposite effect and raises levels of the stress hormone, cortisol.
"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 behaviours," said Marlise Hofer, the study's lead author and a graduate student in the UBC department of psychology.
"Our findings suggest that a partner's scent alone, even without their physical presence, can be a powerful tool to help reduce stress."
The women were randomly assigned to smell a T-shirt that was either unworn, or had been worn by their partner or a stranger. They were not told which one they had been given. The women underwent a stress test that involved a mock job interview and a mental math task, and also answered questions about their stress levels and provided saliva samples used to measure their cortisol levels.
The research team asked women to act as the "smellers" because they tend to have a better sense of smell than men.
They found that :
- women who had smelled their partner's shirt felt less stressed both before and after the stress test.
- Those who both smelled their partner's shirt and also correctly identified the scent also had lower levels of cortisol
- The stress-reducing benefits of a partner's scent are strongest when women know what they're smelling.
- Women who had smelled a stranger's scent had higher cortisol levels throughout the stress test.
"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," said Hofer. "This could happen without us being fully aware of it."
Frances Chen, the study's senior author and assistant professor in the UBC department of psychology, said the findings could have practical implications to help people cope with stressful situations when they're away from loved ones.
"With globalization, people are increasingly traveling for work and moving to new cities," said Chen. "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."