A device that measures nighttime female “erections” to gauge longevity? Now that’s a biohacker’s wet dream.

Every night, Kate Tolo inserts a $15,700 “research grade erection device” into what her boyfriend and business partner, biohacker Bryan Johnson, famously called her “top 1%” vagina.

In fact, both of them wear an erection tracker nightly. Johnson says he’s looking to maintain healthy erections, which some experts agree is a predictor of longevity for men.

And Tolo — despite not having a penis — wants in on the action.

Both Kate Tolo and Bryan Johnson wear an “erection” tracker nightly. Immortals / Kate Tolo

Tolo says women get “erections” too — and it’s possible that tracking them could give ladies similar longevity insights.

She claims to be picking up on research from more than 40 years ago that could pull back the curtain on women’s sexual dysfunction and possibly even show early signs of heart issues, as it does in men.

A bone to pick

Yes, women really do have “erections,” research shows.

During sleep, blood flows to the clitoris, causing it to swell as if aroused. The clitoris is actually very similar to the penis: They are the same organ for the first 2 months of development in the womb.

And using devices similar to Tolo’s — a tampon-shaped light sensor, which she calls her “techno tampon” — research has shown that blood flow in the vaginal tissues does spontaneously surge during sleep, which is also associated with arousal.

“The light sensor inside my probe is the same kind smartwatches use to read your heart rate,” she explained.

That said, it’s been a long time since someone has published research on insights this tech can give us on female health — or improved upon the tech at all, she says. “The tech was invented in 1975 and hasn’t changed in 50 years.”

Tolo’s device costs $15,723.68. Immortals / Kate Tolo

Tolo’s vaginal “erection” data is not easy to get. Her device costs $15,723.68 and is like “lab equipment in my bedroom,” she said.

“I insert the 5cm probe [and] tape a wire to my leg that is plugged into a machine and a laptop. The laptop can’t fall asleep or we lose the data. I sadly learned that through experience.”

Meanwhile, Johnson’s can be bought online for $275 and connects to a smartphone.

“I’ve tracked my nighttime erections for years … It’s one of the best signals I have for vascular health, and it costs $275,” Johnson said. “The gap in our devices sums up the current status of female health.”

“My data is only useful to half the population,” Johnson said of his nightly erection data. “Kate’s is the first serious attempt to publicly publish the other half.” Immortals / Kate ToloWhat the ‘techno tampon’ can tell us

In 1985, a study found that vaginal blood flow changed with sleep stages, heightening during REM. This indicates “a nightly erection cycle,” Tolo said. They also found that all women had nighttime erections — regardless of how easily aroused each participant rated herself.

Tolo says nighttime vaginal blood flow could be a powerful test to see if female sexual dysfunction is something physical or psychological. For example, if blood flow happened unconsciously at night but arousal failed during the day, that could point to a psychological problem.

This test was proposed by researchers in 1985. “It’s so sad that their proposal has been sitting in a journal for 40 years,” she said. “And yet there is still no test, and no easy device.”

The second potential use would be using the “techno tampon” to predict heart issues. Heart disease is the leading cause of death for both men and women.

In men, erectile dysfunction is a known early warning sign of cardiovascular disease. Some experts believe it’s because arteries in the penis are much smaller than in the heart, so plaque build up will appear there first, making it harder to get an erection.

Tolo created “the female protocol” to measure 1,900 biomarkers across blood, urine, stool and vaginal microbiome, while holding diet, sleep and exercise constant. Immortals / Kate Tolo

Tolo argues: Women have the same kind of erectile tissue with similarly small arteries, but no one has followed vaginal blood flow over time to see if it predicts heart disease as it does in men.

“In men, the reasoning behind nocturnal tumescence testing has been that if erections still happen during sleep, the vascular and neurological machinery is intact — though even in men the test is more limited than people assume,” explained Dr. Hillary Seger, a member of Tolo’s care team.

“For women, there is no validated clinical equivalent. Kate’s recordings are the first look I’ve had at how this signal behaves across a full menstrual cycle.”

Tolo has been outspoken about the disparity in research on women’s health.

This year, she created “the female protocol” to measure 1,900 biomarkers across blood, urine, stool and vaginal microbiome, while holding diet, sleep and exercise constant.