Karen Weintraub | Special for USA TODAY

USA TODAY

Anna Swanson isn’t squeamish about admitting that she usually sleeps without clothes.

The 25-year-old public health researcher said she’s just much more comfortable that way, especially in D.C.’s summer heat. She can crank the AC up a little less, and be more environmentally sensitive.

"It feels natural because it is natural and I enjoy it,” said Swanson, a Washington, D.C. resident.

It’s convenient, too. “You wake up the next day and just hop into the shower - there’s less thought to it,” she said.

According to a new survey, Swanson is in the majority, particularly in her Millennial age bracket. Two-thirds of Millennials report sleeping in the nude, the poll by the mattress review site MattressAdvisor.com found.

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Joe Mercurio, a project manager with Mattress Advisor, said he stumbled across several articles suggesting that people sleep better without clothes – and he decided to find out more.

He surveyed over 1,000 people across the country, 58 percent of whom said they sleep in the nude. Nude sleepers also report better sleep quality than pajama-wearers.

Not surprisingly, men are more likely to sleep naked than women – though more than half of women still report sleeping without any clothes. Only 39 percent of Boomers sleep in the buff, compared with nearly 65 percent of Millennials, the survey found.

Relationships seem to relax people’s sleeping habits, with 72 percent of nude sleepers report being in a relationship, compared to only only half of single people. More than half of people who sleep nude report that their partner does, too.

Lack of clothes seems to promote love-making, with nude sleepers reporting substantially more sex than those who prefer to sleep clothed, the study found.

Sleeping nude can sometimes be embarrassing, according to the poll. About half of all nude sleepers admitted to awkward moments, including being walked in on – mostly by a friend, parent or roommate – being bitten by a bug, or having to leave the house unclothed during an emergency.

Nearly 70 percent of respondents who sleep naked said they do so because they’re more comfortable without clothes. About 58 percent said nude sleeping was relaxing, and 54 percent said it improves their sleep. (Roughly 15 percent said they sleep naked to keep their genitals “free and happy.”)

For those who prefer pajamas, their reasons ranged from staying warm, to anxiety about being seen, to “that’s how I was raised.”

Science may fall on the side of modesty, particularly in cold climates.

When we’re sleeping, we lose the ability to tightly regulate our core body temperature, said Alon Avidan, who directs the UCLA Sleep Disorders Center in Los Angeles. If that temperature drops too low, it’s likely to wake us up, disrupting sleep.

The ideal bedroom temperature for most people is 68 to 69 degrees – not to hot, not too cold, he said. Bedrooms should also be dark and devoid of distractions like televisions, laptops and work. “The bedroom should be available only for sleep, sex and sickness and no other activities,” he said.

Avidan said his own preferences change with the season. “I’m more comfortable with less gear, particularly in the summer,” he said. “But boy, when it’s wintertime, I have to have socks on. Just having cold feet is enough to cause me to have a night of bad sleep.”