Iris Krasnow is the author of titles like The Secret Lives of Wives and Surrendering to Yourself. Her newest book is called Sex After ... Women Share How Intimacy Changes as Life ChangesKrasnow interviewed 150 women — ages 20 to 94 — to find out how sexuality figures into the different stages of a woman's life.

"Sex, however you cut it, and sexuality, it's the most intimate thing you can do with another person," Krasnow said. "It's still a deeply emotional experience."

Krasnow said one of the fastest-growing demographics of sexually active people are older women.

"Unfortunately, men do not live as long as women, [and] the fastest-growing segment of the population are women in their early nineties. So I found some great, feisty — mostly living in Palm Springs, and Palm Beach — widows who had only slept with only one person their whole life. And then they lose their dear, departed husband after like 55 years of marriage, and they're dating again for the first time, and they feel like teenagers."

Krasnow's interviewed an 83-year-old woman who had only slept with one man her entire life, and was now dating again.

"She said, 'Honey, it's like I'm a teenager. Now listen, it's not Fifty Shades of Grey sex, but it's very interesting, and it's like I've never had it before.'"

'We're living right now in the real sexual revolution. When we were growing up, the sexiest show on television was 'Love, American Style.''

"We're living right now in the real sexual revolution," Krasnow said. "There's boobs, there's butts, there's bonking on television everywhere. When we were growing up, the sexiest show on television was Love, American Style, and the sexiest scene was Ozzie and Harriet in a hot tub at a nudist colony, and all you saw were shoulders."

Krasnow said that in the middle of this new sexual revolution, a coinciding uptick in Viagra usage hasn't just benefited frisky older couples.

"With all the stress, and trying to make money, and you know, two-career couples trying to balance work and family, a lot of younger men are getting prescriptions for Viagra, too."

Krasnow said there are simple requirements for those seeking to bonk.

"The truth about sexuality and intimacy — and feeling connected to another person — has to be the ability to feel comfortable, and to relax. And that's the drumbeat of every age, and every stage."

>> To hear the entire interview with Iris Krasnow, click the link above.