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He’s away for work again, and the bed feels too big. Before turning out the light, she reaches into the laundry basket, pulls out the T-shirt he wore yesterday and puts it on. It still smells like him.
Plenty of people do something like this and never really think about why. Research suggests that familiar scent may be doing real work, calming the body’s stress response even when the person it belongs to is thousands of miles away.
A shirt, a freezer and a stress test
In a study published in 2018 in the Journal of Personality and Social Psychology, researchers at the University of British Columbia recruited 96 opposite-sex couples. The team was led by graduate student Marlise Hofer and psychologist Frances Chen.
Each man was given a clean T-shirt to wear for 24 hours. He was asked not to use deodorant or scented body products, not to smoke and to avoid certain foods that could change his natural smell. The shirts were then frozen to preserve the scent.
Women acted as the “smellers,” because they tend to have a better sense of smell than men. Each woman was randomly given a shirt to sniff. It was either unworn, worn by her partner or worn by a stranger, and she wasn’t told which.
Then came the hard part. Each woman went through a stress test made up of a mock job interview and a mental arithmetic task, a combination that reliably raises stress in a lab. Researchers measured how stressed the women felt and took saliva samples to track cortisol, the body’s main stress hormone.
Calm from a familiar scent
Women who smelled their partner’s shirt reported feeling less stressed, both before and after the stress test. The effect on the body showed up most clearly in women who correctly guessed the shirt was their partner’s. They had lower cortisol levels, suggesting the calming effect is strongest when the brain recognizes the scent.
The stranger’s shirt had a different effect. Women who smelled it had higher cortisol levels throughout the stress test.
Hofer suggested this may be an ancient response. Humans are wary of strangers from a young age, especially unfamiliar men, and she proposed that a strange male scent might trigger a mild fight-or-flight reaction, possibly without the person even noticing.
Why smell gets straight to the point
Smell has an unusually direct route into the brain’s emotional systems. Most senses pass through a relay station called the thalamus before reaching higher brain areas. Signals from the nose go almost directly to the olfactory bulb and on to emotion-processing regions such as the amygdala.
The amygdala is closely tied to the body’s stress system, the HPA axis. When we sense a threat, the hypothalamus sets off a chain of signals that ends with cortisol being released into the blood.
That direct wiring may help explain the study’s results. A familiar, safe scent could help keep this alarm system quieter. An unfamiliar one could nudge it into action, even if the person isn’t consciously worried.
A habit many people already have
The researchers weren’t the first to notice that people seek out their partner’s smell. A 2006 study by psychologist Donald McBurney and colleagues surveyed people about what they did when separated from a partner. They found that many people, especially women, had deliberately smelled a partner’s clothes during time apart, and said it brought them comfort.
Hofer made the same point in describing her study. Many people wear a partner’s shirt or sleep on their side of the bed when they’re away, she said, without realizing why. The research suggests a possible reason.
What the study didn’t show
The study had limits worth noting. Only women smelled the shirts, so it’s not clear whether men would show the same effect. All the couples were heterosexual, and the study took place in a lab, not in someone’s bed on a lonely night.
The calming effect on cortisol was also strongest only when women correctly identified the scent. And the study measured stress around a single test rather than tracking how quickly women recovered over time.
Still, the findings point to a simple idea. As Chen noted, people increasingly live apart from loved ones because of work and travel. Packing a shirt your partner has worn may be one of the easiest ways to bring a bit of them, and a bit of calm, along with you.
