Can the Smell of a Loved One Relieve Stress?

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People in romantic relationships rely on their partners in all sorts of ways.

Research has certainly demonstrated that positive social support can be just as important as regular exercise and healthy living in ensuring good health. Not only does emotional support make people healthier (mentally and physically), but it can also help in dealing with stress. Whether that support takes the form of physical contact, such as holding hands or hugging, or simply verbal encouragement, having someone to turn to in a moment of crisis can be essential for our personal well-being.

Even when a partner happens to be absent, whether temporarily or following a death, people often rely on physical reminders of that partner for comfort. That reminder can be a photograph, a cherished memento, or a voice recording, but research has shown that the mental representations evoked by these reminders can help reduce emotional pain.

But what about familiar odors? While we all have experiences of memories being awakened by specific odors, can the familiar smell of a romantic partner help people manage stress? Though not as well-researched as the use of visual or auditory reminders, there have been studies examining the psychological benefits of being exposed to the scent of a loved one. One 2006 study showed that 80 percent of women and 50 percent of men deliberately smell the used clothing of their romantic partners while they are away and report feeling comforted by the sensation.

In fact, researchers suggest that the smell of a loved one can produce biochemical changes, including reduced cortisol levels, reflecting the reduced stress they feel. Laboratory studies show that rats, much like humans, experience stress-buffering effects on cortisol levels when they detect the scent of a familiar rat. Studies also show that human infants become much calmer when detecting the scent of their mother's milk. This in turn leads to reduced fussiness and lower cortisol levels.

But could something similar occur with adult humans? A new study published in the Journal of Personality and Social Psychology explores this question by using a rather innovative research design. Marlise K. Hofer of the University of British Columbia and a team of researchers recruited 96 couples for their study after they were deemed to meet basic criteria — in a long-term, heterosexual relationship, no obvious medical problems, and not using hormonal birth control. The average length of the relationships was 2.4 years, and all participants were in their early 20s.

For the purpose of the study, the males acted as "scent donors," providing previously worn t-shirts carrying their scent (having been worn for 24 hours). These were white t-shirts provided by the researchers, to prevent their partners from recognizing them by sight. The males were also instructed to avoid the use of scented products and to refrain from smoking or eating certain foods in order to avoid biasing their scents. The worn shirts were then given to the researchers within five hours of their removal and placed in sealed bags, which were then stored in a freezer to preserve the scent.

As for the women in the study, they were tested to determine where they were in their menstrual cycle and then randomly assigned to one of three experimental conditions. For the first part of the experimental condition, women were given a bag containing a shirt, which they were instructed to smell at different intervals as directed by the experimenter. Depending on the condition to which each woman was assigned, the shirt had either been worn by their husband, by one of the other males in the study, or it had never been worn. All they were told was that the shirt may be "either worn or unworn, according to the condition you were randomly assigned to ... there is a low probability that the shirt you smell has been worn by someone you know.” They also completed questionnaires measuring their level of perceived stress and provided saliva samples to be measured for cortisol levels.

All female participants then completed a 10-minute mock job interview for which they only had five minutes to prepare. To make the interview as stressful as possible, the women were seen individually by two judges in white lab coats who provided no feedback or encouragement. Each interview was videotaped and followed a prepared format to ensure that all women had the same experience. Immediately following the interview, the women were led back to the original testing room, where they completed questionnaires measuring perceived stress and their impressions of the experiment (whether or not they were aware the shirt belonged to their spouse). Saliva samples were also taken to determine the change in cortisol levels before and after the interview condition.

The results showed that women who were exposed to their partner's scent reported significantly less perceived stress than women who were either exposed to a stranger's scent or to an unworn shirt. The greatest stress relief from scent exposure occurred immediately before the interview (anticipatory phase) and immediately after (recovery phase). While the measures of cortisol levels were largely consistent with the perceived stress results, there were also some interesting differences. Women who were exposed to a stranger's scent showed increased stress compared to women exposed to a partner's scent or an unworn shirt. This suggests a "stranger danger effect," though it only seemed to apply to cortisol levels and not actual perceived stress in the participating women.

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While these results do suggest a "partner comfort" effect at work, at least with perceived stress immediately before or after a stressful event, it still isn't clear why this isn't reflected by cortisol levels. Though other researchers have noted that perceived stress and cortisol levels don't necessarily go together, they often do in stressful situations. One possibility raised by Hofer and her colleagues is that some women may not be able to tell the difference between their husband's scent or the scent of a stranger based on smell alone. While 63 percent of the women were able to identify their husband's scent correctly, a sizable minority could not. That might be skewing the results somewhat as far as cortisol levels are concerned.

Hofter and her colleagues recognize that much more research is needed to explore the link between partner scent and stress relief, including whether similar results could be obtained for men as for women. (Women were used in this study because their sense of smell is more sensitive.)

Also, since the women in this study were all at about the same stage in their menstrual cycle, future research is needed to see if the same effect holds up through different menstrual phases, as well as whether similar findings exist for same-sex relationships and for individuals related in other ways (family, friends, etc.). It might also be interesting to look at how comforting scents may help provide other benefits of social support, including good sleep and healthy eating.

As Hofter et al. point out in their conclusions, the increasingly global nature of modern life means that we are often separated from our usual social support networks for weeks or even months at a time. In 2016 alone, U.S. residents took an estimated 2 billion trips, and people often move to new cities or states for work purposes. Could something as simple as traveling with a used article of clothing from a loved one help reduce separation anxiety and make it easier to cope with stressful situations?

As I said at the beginning, people in romantic relationships rely on their partners in all sorts of ways. For many people, stress relief may be just a sniff away.