If for whatever reason your significant other is away for Valentine’s Day, you might at least dust off one of their old shirts and tuck yourself in with it — it might help you sleep better, according to a new study by psychologists at the University of British Columbia.
The researchers analyzed sleep data from 155 participants who were offered two identical-looking t-shirts to use as pillowcases. One had been previously worn by their long-term romantic partner and carried their scent. The other had either been previously worn by a stranger or was entirely clean of any foreign scent.
The participants’ partners who had to wear the T-shirt for 24 hours were asked to refrain from using any products that might alter their natural odor, such as deodorant or cologne, as well as engaging in exercise, eating certain foods that may affect body odor, or smoking. The shirts were then frozen after they were handed over to the researchers in order to preserve their scent.
When the participants were given the two shirts to place over their pillows, they weren’t told which one carried their partner’s scent.
For two consecutive nights, the participants had to sleep with each T-shirt over their pillow. Then, in the morning, they had to complete a survey that measured how well-rested they felt.
The researchers also employed an objective measure of sleep quality by strapping an actigraphy sleep watch to the participants’ wrist, which measures their movements through the night.
Finally, at the end of the study, the participants had to guess whether any of the two shirts they slept on belonged to their partner.
Remarkably, even though their partner wasn’t physically present, the participants reported sleeping better when they thought they were exposed to their partner’s scent overnight.
“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 percent,” said Marlise Hofer, the study’s lead author and a graduate student in the University of British Columbia’s 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.”
Regardless of whether or not the participants self-reported better sleep, data from the sleep watches showed that participants actually improved their sleep quality when they were 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 authors say that the findings can be explained by the fact that the physical presence of a romantic partner is known to be associated with feelings of safety, calm, and relaxation. As a proxy, a partner’s scent can transfer some of these psychological benefits even when they’re not physically present.
In the future, the researchers would like to perform a similar study, this time investigating whether the scent of parents can improve an infant’s sleep. But, for now, a simple takeaway is that bringing a partner’s scarf or shirt along when traveling may have measurable effects on our sleep.
The findings were reported in the journal Psychological Science.
