In a new study, researchers found that the scent of a romantic partner can improve sleep.
They found study participants who were exposed to their partner’s scent overnight experienced better sleep quality, even though their partner was not physically present.
The findings provide new evidence that merely sleeping with a partner’s scent improves sleep efficiency. The participants had an average sleep efficiency improvement of more than 2%.
The research was conducted by a team from the University of British Columbia.
In the study, the team 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 others had either been previously worn by a stranger or were clean.
To capture body odor 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 odor.
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.
The team says one of the most surprising findings is how a romantic partner’s scent can improve sleep quality even outside of conscious awareness.
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 linked to positive health outcomes such as a sense of safety, calm and relaxation, which in turn leads to better sleep.
By signaling recent physical proximity, the mere scent of a partner may have similar benefits.
The team 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 lead author of the study is Marlise Hofer, a graduate student in the UBC department of psychology.
The study is published in the journal Psychological Science.
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