Lehmiller tells Men's Health, "Men and women alike fantasize about more than just a mechanical sex act. We're looking for a certain level of emotional fulfillment, too, whether thats feeling desired or attractive, feeling sexually competent, or feeling connected to another person."

He continues, "Its a lot easier to envision feeling those emotions when youre fantasizing about someone you know as opposed to someone youve never met."

For his latest book, Tell Me What You Want: The Science of Sexual Desire and How It Can Help You Improve Your Sex Life, Lehmiller surveyed over 4,000 people about their sexual fantasies.

Ninety percent of his participants said they had fantasized about a romantic partner before, whereas only two-thirds had fantasized about a celebrity. Additionally, while 51% said they fantasize about their romantic partners often, a mere 7% said they fantasize about celebrities often.

But when we are thinking about celebrities, who pops up in our mind?

The top 5 female celebrities men fantasize about are:

  1. Scarlett Johansson
  2. Jennifer Aniston
  3. Jennifer Lawrence
  4. Kate Upton
  5. Sofia Vergara

Women who fantasize about female celebrities actually have similar tastes to men. The top 5 female celebrities women fantasize about are:

  1. Scarlett Johansson
  2. Angelina Jolie
  3. Mila Kunis
  4. Jennifer Lawrence
  5. Megan Fox

The top 5 male celebrities woman fantasize about are:

  1. Channing Tatum
  2. Ryan Gosling
  3. Adam Levine
  4. Geroge Clooney
  5. Brad Pitt

Again, it seems like men and women have similar tastes when fantasizing about male celebrities as the top 5 male celebrities men fantasizes about are:

  1. Zac Efron
  2. Jake Gyllenhaal
  3. Channing Tatum
  4. Ryan Gosling
  5. Henry Cavill

So is it bad to fantasize about celebrities, especially if you're in a committed relationship?

According to Lehmiller's research, it depends.

It could mean that you're "not satisfied in your current relationship. When people arent happy with their love lives, they tend to fantasize more about people other than their current partners," Lehmiller explains. "At the same time, though, frequent celebrities fantasies could also mean that you just have a very active imagination. People with overactive imaginations have more fantasies regarding just about everything simply because theyre always thinking."

Perhaps the key to a health relationship is to fantasize having a threesome with Scarlett Johansson and your wife.