men and women dream about sexual encounters about 8% of the time.
While the amount of randy dreams may be the same, there was a distinct difference in content. Women were twice as likely to dream about sex with public figures and more women dreamed about sex with previous or current partners. Men leaned toward the adventurous side and were more likely to dream about multiple partners or sex in public places.
A similar study was conducted 40 years ago. At that time, women reported significantly fewer sex dreams than men. Researchers at the time assumed that meant women didn't fantasize about sex as much.