Couples, take heed: A happy wife equals a happy sex life. If you’re a guy in a straight, married relationship and you want more sex, it turns out — again — that sharing housework is the key.

In a recent study of straight couples in the United States, those who divided the housework equally had sex 6.8 times each month. Couples in which one partner (guess which one) did the majority of household tasks had sex 5 times a month.

The study will be published soon in the Journal of Marriage and the Family.

This finding is not new. Back in 1989, award-winning sociologist Arlie Hochschild wrote a book called The Second Shift, in which she documented the fact that women in straight relationships wound up doing much more than their share of the housework and the childcare. Even if they worked outside the home, earning in money in a career, they still had a “second shift” when they came home — taking care of the kids, shopping, cooking and cleaning.

In a recent interview, Hochschild didn’t quite agree with the picture painted by the new studies. She says the division of labor in the home has certainly improved, but that women are still doing twice as much housework and childcare as men.

I imagine that the correlation between housework equality and interest in having sex is evident to most women. It’s not just that doing all the housework can make you tired, housework is also boring and tedious.

To understand the sexual science behind these studies, you only have to know one simple fact proven by the sexological research: Angry men still are horny. As annoyed or upset as men feel, their sex drive tends to be constant. Angry women, on the other hand, are not horny.

Remind yourself of that fact, guys, as you fold the towels.