People tend to toss and turn less during sleep when they can smell the scent of their long term partner, according to new research published in the journal Psychological Science.
“Close contact with loved ones is known to have positive effects on health (reductions in stress, improved sleep, etc.). I was interested in how loved ones impacted health outcomes and whether their scent alone could carry similar benefits,” explained Marlise Hofer, the corresponding author of the study.
Hofer and her co-author, Frances Chen, first had one member of a heterosexual couple in a long-term relationship wear a plain cotton T-shirt for 24 hours. During this time, the wearer was asked to avoid activities that could alter their usual scent, such as eating spicy food or doing vigorous exercise. They were also told to avoid perfume, cologne, and antiperspirants.
The researchers then gave the second member of the couple two identical shirts. One had been previously worn by their partner and another had either been previously worn by a stranger or was scent free — but the participants were unaware of which shirt was which. The second member of the couple then slept with one shirt placed over their pillow for the following 4 nights. The participants wore an actigraphy device on their wrist to record their sleep/wake intervals.
The study included 115 participants.
After controlling for attachment style, relationship length and quality, stress level, day of the week, order of scent exposure, and type of control scent, the researchers found that exposure to the scent of a partner was associated with increased sleep efficiency. When a participant used their partner’s scent-bearing T-shirt, they experienced an average of over nine additional minutes of sleep per night.
“The effect we observed in our study was similar in magnitude to that reported for melatonin supplements—a commonly used sleep aid. The findings suggest that the scent of our loved ones can affect our health in powerful ways,” Hofer said.
When participants believed that they were sleeping with their partner’s scent, they reported better sleep quality. But the participants misidentified their partner’s scent about 30% of the time and exposure to the actual scent of a partner did not significantly increase the participants’ self-perceived sleep quality.
“I think the most interesting aspect of our results was that the effects we found were outside of conscious awareness. Participants did not self report that their sleep was improved, however the sleep watches showed improvements in sleep on nights when the partner’s scent was present,” Hofer told PsyPost.
“This is the first paper to examine whether the scent of a loved one improves sleep, and more work is necessary replicating these effects before we can be confident about the result. However, our results indicate that sleeping with a romantic partner’s scent may improve sleep. If people are having trouble sleeping when their partner is away, they can try bringing their partner’s worn shirt to bed (it may help and is unlikely to have any negative consequences!)”
“As mentioned above, the results are preliminary. In addition, the sample consisted of mainly young adults (mid 20s) and was primarily female. Thus, an important future direction is to examine if this effect emerges in different populations,” Hofer added.
The study, “The Scent of a Good Night’s Sleep: Olfactory Cues of a Romantic Partner Improve Sleep Efficiency“, was authored by Marlise K. Hofer and Frances S. Chen.
