When the weather gets cold, you might reach for thick pyjamas. However, according to experts, it could be better to strip down rather than layer up.
“There is an optimal temperature in the sleeping environment which ranges from 16-18 degrees,” explains certified somnologist Dr Ana Brito from the European Sleep Research Society.
“For sleep to be restorative, our bodies need to be cool. Body temperature goes down while we sleep by about two degrees, it’s part of going into ‘energy saving mode’. Sleeping naked makes it easier to regulate temperature and get to that optimal point.”
The merits of nudity versus pyjamas in bed haven’t been studied extensively, but some research shows benefits to sleeping naked. “Overheating to the point of sweating because of synthetic, uncomfortable pyjamas will wake you up during the night,” Dr Brito explains.
Happily for pyjama-wearers, Dr Guy Meadows of Sleep School says it isn’t necessarily the worst thing to do.
“Sleeping naked has benefits such as regulating body temperature, preventing overheating and offering a less restrictive and more comfortable experience,” confirms Dr Meadows. “On the other hand, sleeping in pyjamas can provide insulation, particularly in colder climates. Find what feels comfortable, considering factors like body temperature preferences and climate.”
For those willing to eschew their pyjamas there may be other benefits to sleeping nude…
For the body to be able to properly release melatonin, the hormone that brings on sleep and keeps us unconscious through the night, it needs to be cool. “If you’re too hot while you’re trying to sleep, your body won’t release as much melatonin so you’ll find it harder to get to sleep, but also to stay asleep,” says Sammy Margot, a chartered physiotherapist and sleep expert for bed company Dreams. “If you want to sleep more deeply, staying cooler by sleeping naked or in a cold room will help.”
Margot notes that everyone will have a different set point at which they start feeling the cold. If you grew up in a warmer climate, you’ll feel the cold more than someone who is used to a temperate climate. However, just like with cold-water bathing or wild-swimming, you can gradually expose yourself to cooler temperatures that should help you sleep.
If you’re prone tofeeling the cold but still want the benefits of sleeping nude, there is a solution. “Research shows that if your peripheries are cold, that may cause more frequent night awakenings,” says Margot, who says her hands and feet feel physically painful if they get too cold. “So at this time of year, I’d advise people to sleep naked, but wear bed socks – a very attractive look, I know, but it may improve your sleep.”
Increased anti-ageing hormones
Once your body is in deep sleep, it can start restorative work, repairing damaged cells. It does this by releasing Human Growth Hormone (HGH).
HGH can reverse signs of ageing by restoring cells in the skin, hair, muscles, bones, and other tissues. It also reduces blood pressure and could boost your workout. A 2011 study from Stanford University found that higher amounts of HGH from better sleep improves athletic performance.
Not getting enough sleep, perhaps through being too hot in bed, impedes the release of HGH. Researchers at Warwick University found that those who sleep for less than six hours each night are three times as likely to develop type 2 diabetes or heart disease. This is because cortisol, the stress hormone, and ghrelin, the hunger hormone, both surge so you’ll be more tempted to eat and have poorer control over your appetite when you do.
“There’s evidence to suggest that women who sleep naked are less likely to develop yeast infections,” says Margot. “You need adequate air circulation to prevent candida, a natural yeast from flourishing in the vagina. You tend to see women who wear tight or synthetic underwear or bedwear which doesn’t allow much airflow developing these conditions.
“For men, there was a 2015 study from Stanford University which found men who go nude at night had 25 per cent less DNA fragmentation in their sperm compared with men who wore tight briefs day and night,” adds Margot. “We know men who keep their testicles cool have better sperm quality. Wearing underwear to bed increases the temperature of the scrotum which can decrease sperm vitality and count.”
“Sleeping naked with a partner may increase connection,” says Margot. “Evidence suggests that partners who spend time in skin-to-skin contact release more oxytocin, the hormone associated with love that makes you feel good. It can also help to reduce anxiety, so that will also improve your sleep.”
Higher levels of oxytocin also have positive effects on sexual responsiveness and some research shows it can improve orgasms too.
Even for singletons, there’s a benefit to spending more time without clothes. A study from Goldsmiths University found that being nude improves self-esteem.
What if you really don’t want to sleep naked?
If you don’t want to sleep naked, choose nightwear made with natural fibres. “Linen, bamboo, or silk,” advises Dr Lindsay Browning, neuroscientist and sleep expert at And So To Bed. “These fabrics will wick off sweat and keep you dry and cool at night. This will be particularly important for women suffering from night sweats in the menopause.”
And there are benefits to non-nude sleeping too. Pyjamas may improve the lifespan of your bed linen, says Dr Browning. “If you sleep naked, then dead skin cells and sweat will go directly into the bedsheets leading to a build-up of bacteria and potential bedbugs and mites, whereas pyjamas will absorb that,” she says.