Have you ever felt reassured by the smell of your partner’s clothes? Does that comfort arise from body odor itself, or do recognizing it as the smell of someone you love and memories of time together also play a part?
A study published by Franny B. Spengler and colleagues in 2026 delivered partners’ natural body odors in a way that was difficult to consciously notice, testing whether they eased stress. The findings differed from the researchers’ original expectations.
Delivering a partner’s body odor alone through a device
Participants were heterosexual couples who had been together for at least a year and had good-quality relationships. Measurements began with 110 couples, or 220 people. After exclusions for unmet criteria, technical problems, and other reasons, the analysis included 179 people: 91 women and 88 men. Missing recordings meant heart-rate analyses used data from 146 people.
Body odor was collected by having participants wear T-shirts with cotton pads attached at the armpits for five nights. Collection conditions were standardized, including avoidance of scented products. This was intended to isolate natural body odor as far as possible, rather than the smell of everyday clothing that also contains perfume or fabric softener.
During the experiment, a device connected to the nose delivered either air containing the partner’s body odor or air passed over a control pad without body odor. Participants were also assigned to a stressful task or a less demanding task. Odor–task combinations were randomized, and neither participants nor experimenters were told which odor was being delivered.
This was not an experiment in which partners supported each other in the same room. Each member of a couple was tested separately.
Measuring interview and mental-arithmetic stress in three ways
The stress-inducing task involved a mock job-interview speech and difficult mental arithmetic, performed while being filmed in front of evaluators who gave little response. In the control condition, participants talked about a holiday and performed easy calculations without evaluators or a camera.
Odor was initially presented for one minute and then during 10 minutes of preparation and the 10-minute task. The researchers measured perceived stress, heart rate, and salivary cortisol. Cortisol indicates the hormonal stress response, but it does not necessarily change in the same way as mood or heart rate.
The responses did not converge on reassurance
Among those performing the stressful task, perceived stress was higher with partner odor than with the control odor. The difference was already present at the measurement after initial odor exposure, before preparation began, and diminished during recovery after the task.
In other words, the finding was not that body odor made stress rise more steeply during the task. Rather, stress levels differed from an early point after odor presentation.
Heart rate was also higher with partner odor, particularly while participants performed the stressful task. Cortisol, however, showed no detectable clear change due to partner odor.
Under these conditions, body odor alone did not support stress relief: subjective experience and heart rate instead shifted upward. Stress did not increase across all three indicators, however.
A faster heart rate does not necessarily mean dislike
The authors consider several explanations. One involves responses associated with attraction or sexual arousal toward a partner. Participants may have attributed bodily changes such as a faster heart rate to the stressful task in front of them and consequently felt more stressed.
Exploratory analysis also found an association: people who generally found their partner’s body odor more sexually attractive showed a larger odor-related heart-rate increase during the task. Sexual arousal itself was not directly measured during the experiment, however, so this mechanism was not established.
Another hypothesis is that sensing a loved one’s presence through odor makes the body more active in a stressful situation. The person may feel that their partner is also involved in the threat, strengthening a preparatory response. This, too, is an explanation the authors propose from their data.
Recognizing whose smell it is becomes another question
The authors emphasize the distinction between odor itself and the context in which it is received. Picking up and smelling clothing may also involve recalling the partner and expecting comfort. Such meanings may have contributed to the comforting effects observed in earlier studies.
However, this experiment did not directly compare being told that an identical odor belonged to the partner with not being told. It cannot establish that conscious recognition is essential for reassurance.
The participants were mainly young heterosexual couples in good-quality relationships. Because the study did not compare the odors of strangers or close people other than romantic partners, it is also uncertain whether the response is specific to a partner’s body odor. Continuous laboratory odor presentation cannot be applied directly to everyday hugs or enjoyment of a favorite perfume.
Summary
In this experiment, a partner’s body odor did not act as an automatic stress-relieving signal. Self-rated stress and heart rate were higher, while cortisol showed no clear odor effect.
These differences show that the effects of a familiar person’s odor cannot be captured by a simple ‘calming action’. Evoking comforting memories, feeling attracted to a partner, and preparing for tension in the current situation may all be relevant. The next step is to investigate which responses predominate in relation to odor recognition and context.
References
Spengler, F. B., Doerflinger, J. T., Noel, J. A., Ditzen, B., Freiherr, J., & Heinrichs, M. (2026). Smelling the romantic partner’s natural body odor increases psychological and autonomic but not cortisol stress responses. Scientific Reports, 16, 1760. DOI: 10.1038/s41598-025-27639-w (Full original article).
The study was conducted with internal funding from the University of Freiburg and reported no external funding. The authors declared no competing interests. Original article: © The Author(s) 2026, CC BY 4.0.
