Sex is the fountain of youth.

So says a British psychologist, who claims that people who get lots of action looked anywhere from five to seven years younger than those who don’t.

“My message is that lovemaking is good,” Dr. David Weeks told the British Psychological Society.

Former head of old age psychology at the Royal Edinburgh Hospital, Weeks said he spent a decade prying into the private lives of thousands of men and women of all ages.

Weeks found that sexual pleasure is a “crucial factor” in preserving youth.

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How? Lovemaking releases the human growth hormone, which helps keep the skin elastic and thus less likely to wrinkle, he said.

Sex also released endorphins, which are the body’s feel-good chemicals and natural painkillers that ease anxiety and make it easier to sleep, Weeks added.

Nookie boosts blood circulation, which is good for that heart and gives skin that healthy glow, the good doctor said.

Finally, sex burns fat and releases other chemicals that bolster the immune system, he said.

Weeks, who is himself a youthful-looking 59-years-old, said getting it on is especially good for geezers.

Getty Images

young couple in bed

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“Sexuality is definitely not the prerogative of younger people and nor should it be,” he said. “Sexual satisfaction is a major contributor to quality of life.”

Out in Brooklyn, Marissa Martinez said she’s all for improving the quality of her life.

“How much younger?” asked Martinez, who was strolling through Bay Ridge with her husband Conrad — and who declined to give her age. “Anything helps.”

But Conrad Martinez wasn’t having it.

“I’m trying to look older,” said Martinez, who is 50 and sported a salt and pepper beard. “I’m trying to look distinguished. I thought about getting a pipe.”

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Besides, he said, “Younger people do it all the time.”

Outside a bodega on Fourth Ave., Ron Nelson, 74, and Heather Polamis, 52, said Dr. Weeks has the right prescription.

“It’s a positive thing, makes you happy, makes you laugh, cures depression,” said Polamis, who admitted she only has sex once every three years or so.

Nelson said he’s game but added, “At my age, you have summertime sex.”

“Some of the time it works, some of the time it don’t,” he said.

csiemaszko@nydailynews.com