While some count sheep to help them nod off, new research suggests smelling your lover’s T-shirt could be the key to a peaceful night’s sleep.
Scientists from the University of British Columbia in Vancouver had 155 people sleep on a pillow covered with a clean t-shirt or one worn by their other half.
The following morning, the participants rated their sleep quality, which improved among those who nodded off on their partner’s clothing.
Unwinding to a lover’s scent is thought to give a sense of safety and calm, aiding shut eye.
“Our findings provide new evidence that merely sleeping with a partner's scent improves sleep efficiency,” said lead author Marlise Hofer.
“Our participants had an average sleep efficiency improvement of more than 2%.
“We saw an effect similar in size to what has been reported from taking oral melatonin supplements, often used as a sleep aid.”
Melatonin is a natural hormone that regulates sleep patterns.
A manmade version is available on prescription only on the NHS to treat short-term sleep problems.
In the US, around 30% of people complain of “sleep disruption”, while 10% have “symptoms of daytime functional impairment consistent with insomnia”.
The physical presence of a lover has been shown to make people feel safe, relaxed and calm.
To uncover whether a lover’s odour could aid sleep, the scientists gave the participants two identical-looking T-shirts.
One had previously been worn by their partner, while the other had been worn by a stranger or was clean.
The T-shirt wearers were told not to use deodorant or take part in activities that could affect body odour, like smoking or exercise.
The clothing was then frozen to capture the scent.
Once thawed, it was used as a pillowcase. The participant slept with either this or the “placebo” shirt across two consecutive nights.
The next day, they completed a survey that asked how rested they felt.
A “sleep watch” also monitored their activity throughout the night.
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Results show the participants felt more well rested if they guessed they were sleeping on their partner’s T-shirt.
Data from the sleep watches also reveals the quality of their shut eye improved when the participants were exposed to their other half’s scent.
The results will be published in full in the journal Psychological Science.
“One of the most surprising findings is how a romantic partner's scent can improve sleep quality even outside of our conscious awareness,” said study author Dr Frances Chen.
“The sleep watch data showed 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 scientists hope their results will lead to simple, effective ways of improving sleep, like taking a partner’s T-shirt with you when you travel.
They are recruiting participants for a study that will look at whether the scent of a baby’s parents helps the infant nod off.