Summary: Exposure to a romantic partner’s scent during sleep can improve sleep quality, even when the partner is not physically present.
Source: University of British Columbia
New research from the University of British Columbia suggests that the scent of a romantic partner can meaningfully improve sleep quality.
In a controlled sleep study, researchers found that participants who slept with the scent of their romantic partner experienced measurable improvements in sleep efficiency and reported feeling more rested the following morning. The benefit occurred even when the partner was not in the same room.
Lead author Marlise Hofer, a graduate student in UBC’s department of psychology, reported that participants showed an average improvement in sleep efficiency of more than two percent. “We saw an effect similar in size to what has been reported from taking oral melatonin supplements – often used as a sleep aid,” Hofer said.
The study included 155 participants who each received two visually identical t-shirts to use as pillowcases across four nights. One shirt had been worn by the participant’s romantic partner for 24 hours under controlled conditions to capture natural body odor; the partner was asked to avoid deodorant, scented products, smoking, exercise and certain foods during that time. The worn shirts were frozen to preserve scent. The comparison shirt was either clean or had been worn by a stranger.
Participants slept two consecutive nights with each shirt, without being told which shirt came from their partner. Each morning they completed a survey rating how rested they felt, and objective sleep was recorded with an actigraphy sleep watch. Actigraphy tracks movement across the night to estimate sleep onset, awakenings and sleep efficiency—the proportion of time spent asleep while in bed—which is a commonly used objective measure of sleep quality. At the end of the study participants also guessed whether the shirts they slept with had belonged to their partner.
Self-reports and objective measures showed complementary findings. Participants tended to report feeling more well-rested on nights when they believed they were sleeping with a partner’s scent. More importantly, the actigraphy data indicated that nights with actual partner scent exposure were associated with reduced movement and improved sleep efficiency, regardless of participants’ conscious awareness of the scent’s origin.
“The sleep watch data showed that participants experienced less tossing and turning when exposed to their partners’ scent, even if they weren’t aware of whose scent they were smelling,” said Frances Chen, the study’s senior author and an associate professor in UBC’s department of psychology.
The researchers suggest several plausible mechanisms. Long-term romantic partners can provide feelings of safety, calm and emotional security; those benefits are known to support restorative sleep. A partner’s scent may signal recent physical proximity and social safety, triggering subconscious processes that reduce arousal and nighttime movement, which in turn improves sleep quality.
These findings point to a simple, non-pharmacological intervention that could help some people sleep better—an idea that could be especially useful when traveling or sleeping apart from a partner. Hofer noted that carrying a partner’s shirt when traveling alone might be an easily accessible way to enhance rest.
The research team is expanding the work and is currently recruiting participants for a pilot study that will test whether parental scent similarly improves infant sleep. The present findings have been accepted for publication in Psychological Science.
Funding: The research was supported by an American Psychological Foundation Visionary Grant, a UBC graduate student research award and a Canadian Natural Sciences and Engineering Research Council Discovery Grant.
Source:
University of British Columbia
Media contacts:
Wan Yee Lok – University of British Columbia
Image source:
The image is in the public domain.
Original research: The study will appear in Psychological Science.