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ABC News' Nikki Battiste and Dan Harris report:

The latest way to improve your love life doesn't involve a slick how-to guide. It doesn't involve Big Pharma, either.

It's yoga.

According to William Broad, author of "The Science of Yoga," which came out Feb. 7, there is real evidence yoga helps sex.  For example, the cobra pose boosts blood flow to the pelvis.

"Why spend millions on those little blue pills, right?" Broad said in an interview with ABC News' Dan Harris.

Broad, a science writer for The New York Times, spent years combing through the scientific literature on yoga.

"I can cite you study after study after study," Broad said. "We can go through hormones, brain waves, vaginal blood flow…"

Broad said yoga started in medieval India as a sex cult, a series of practices that used our sexual energies as the fast track to enlightenment.

Broad said he was familiar with the "yogasm," a term coined by the HBO's "Sex and the City" to mean yoga-induced orgasm. Yogasms are now the topic of scientific study, he said.

Scientists at Rutgers University are conducting brain scans on women who lie under fluorescent lights, close their eyes and enter states of orgasmic bliss. The physical signs are visible on monitors, Broad said.

"[Y]ou can get into states where you are orgasmic without touching yourself," he explained.  "In the clinical literature, it's called spontaneous orgasm. In the popular world, it's called 'thinking off.'"

Watch the full story on "Nightline" tonight at 11:35 ET/10:35 CT