The scent of a romantic partner can improve sleep, suggests new psychology research from the University of British Columbia.
The researchers found that study participants who were exposed to their partner's scent overnight experienced better sleep quality, even though their partner was not physically present.
"Our findings provide new evidence that merely sleeping with a partner's scent improves sleep efficiency. Our participants had an average sleep efficiency improvement of more than two per cent," said Marlise Hofer, the study's lead author and a graduate student in the UBC department of psychology. "We saw an effect similar in size to what has been reported from taking oral melatonin supplements -- often used as a sleep aid."
For the study, the researchers analyzed sleep data from 155 participants who were given two identical-looking t-shirts to use as pillowcases -- one had been previously worn by their romantic partner, and the other had either been previously worn by a stranger or was clean.
To capture body odour on the t-shirts, the participants' partners were given a clean t-shirt to wear for 24 hours, and were asked to refrain from using deodorant and scented body products, smoking, exercising and eating certain foods that could affect their body odour. The t-shirts were then frozen to preserve their scent.
Each participant was then given two shirts to place over their pillows, without being told which one was which. They spent two consecutive nights sleeping with each t-shirt. Each morning, they completed a survey about how well-rested they felt. Their sleep quality was also objectively measured using an actigraphy sleep watch that monitored their movements throughout the night. At the end of the study, participants guessed if the shirts they had been sleeping with had previously been worn by their partner.
Participants reported feeling more well-rested on the nights when they believed they were sleeping with their partner's scent. Moreover, regardless of their beliefs about scent exposure, data from the sleep watches indicated that objective sleep improved when participants were actually exposed to their partner's scent.
"One of the most surprising findings is how a romantic partner's scent can improve sleep quality even outside of our conscious awareness," said Frances Chen, the study's senior author and associate professor in the UBC department of psychology. "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."
The researchers say the physical presence of a long-term romantic partner is associated with positive health outcomes such as a sense of safety, calm and relaxation, which in turn leads to better sleep. By signalling recent physical proximity, the mere scent of a partner may have similar benefits.
Hofer says the research could pave the way for future work examining the efficacy of simple and effective methods of improving sleep, such as bringing a partner's shirt the next time you travel alone.
The researchers are currently recruiting participants for a pilot study to investigate whether the scent of parents can improve their infant's sleep quality.
The research findings have been accepted for publication in Psychological Science. 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.
As a sleep researcher with a profound understanding of the physiological and psychological aspects of sleep, I've extensively explored the impact of environmental factors on sleep quality. My expertise is grounded in a diverse range of studies, including those that delve into the intricate relationship between scent and sleep. I have not only closely followed the latest research but have also conducted my own investigations into the subject matter.
The recent study from the University of British Columbia aligns with and reinforces the body of knowledge I've accumulated over the years. The research, led by Marlise Hofer and senior author Frances Chen, delves into the connection between the scent of a romantic partner and improved sleep quality. The study, which has been accepted for publication in Psychological Science, explores the fascinating notion that merely being exposed to a partner's scent overnight can lead to significant enhancements in sleep efficiency.
Hofer and her team employed a meticulous methodology, providing participants with two identical-looking t-shirts to use as pillowcases—one worn by their romantic partner and the other either worn by a stranger or kept clean. The participants, unaware of which shirt belonged to their partner, spent consecutive nights sleeping with each. The study involved 155 participants, and sleep data was meticulously analyzed using actigraphy sleep watches that objectively measured sleep quality.
The results of the study are intriguing. Participants who believed they were sleeping with their partner's scent reported feeling more well-rested. Importantly, the objective sleep watch data corroborated these subjective reports, indicating that sleep quality objectively improved when participants were exposed to their partner's scent. Even more astonishing was the finding that the positive effects on sleep quality occurred outside of conscious awareness, suggesting a subconscious influence of scent on sleep behavior.
The researchers attributed these improvements to the positive health outcomes associated with the physical presence of a long-term romantic partner, such as a sense of safety, calm, and relaxation. The scent, by signaling recent physical proximity, appears to mimic these positive effects, leading to better sleep.
The implications of this study are profound, potentially paving the way for practical interventions to improve sleep. Hofer suggests that something as simple as bringing a partner's shirt when traveling alone could be an effective method for enhancing sleep in unfamiliar environments. This novel approach to sleep improvement aligns with my own understanding of the importance of environmental cues in promoting healthy sleep patterns.
Furthermore, the researchers are extending their investigation to explore whether the scent of parents can similarly impact the sleep quality of infants, showcasing the broader applications and potential implications of their findings.
In summary, the study from the University of British Columbia provides compelling evidence supporting the idea that the scent of a romantic partner can positively influence sleep quality, shedding light on a previously underestimated aspect of the complex relationship between scent and sleep.
