According to new University of British Columbia psychology research, participants who were exposed to their partner’s scent overnight had better sleep quality, even though their partner was not physically present.
The study’s principal author, Marlise Hofer, stated: “Our findings provide additional evidence that simply sleeping with the aroma of a mate enhances sleep efficiency. Our participants improved their sleep efficiency by more than 2% on average. We observed a sizeable effect similar to that seen with oral melatonin pills, which are commonly used as a sleep aid.”

Researchers analysed sleep data from 155 people who were given two identical-looking t-shirts to use as pillowcases – one had previously been worn by their love partner, and the other had either been worn by a stranger or was clean.
To capture body odour on T-shirts, participants’ partners were given a clean t-shirt to wear for 24 hours and advised to refrain from using deodorant and scented body products, smoking, exercising, and eating certain meals that could alter their body odour. The T-shirts were then frozen in order to keep their smell.

Each participant was then given two shirts to wear over their pillows without knowing which was which. They slept in each T-shirt for two nights in a row. Every morning, they filled out a survey on how well-rested they were.
Their sleep quality was also objectively assessed using an actigraphy sleep watch, which tracked their movements throughout the night. At the end of the experiment, participants guessed whether the shirts they were sleeping in had previously been worn by their partner.

Participants felt more rested on nights when they thought they were sleeping with their partner’s fragrance. Furthermore, independent of their opinions regarding smell exposure, data from the sleep watches showed that when participants were really exposed to their partner’s scent, objective sleep improved.
“One of the most startling findings is that the aroma of a romantic partner can increase sleep quality even when we are not aware of it. The sleep watch data revealed that when individuals were exposed to their partners’ scent, they had less tossing and turning, even if they were unaware of whose perfume they were smelling “Frances Chen, an associate professor at UBC, agreed.

The physical presence of a long-term love partner is also connected with favourable health outcomes such as a sense of safety, serenity, and relaxation, which leads to improved sleep, according to the study. The mere aroma of a spouse may have similar effects by signalling recent physical proximity.
According to Hofer, the study could open the way for future research into the usefulness of simple and effective sleep-improvement strategies such as packing a partner’s shirt the next time you travel alone.