We know the very best time to have sex…

You climb into bed, shimmy up next to your S.O., and pucker up—only to find that they’ve already cashed in their ticket to Snoresville. If you’re in a long-term relationship, chances are it’s a familiar scenario, particularly if your partner is of the opposite sex. As the Daily Mail reports, a 2015 study of 2,300 people by the sex toy brand Lovehoney found that male sexual desire peaks between 6 and 9 a.m., aligning with the highest spike in their testosterone levels over a 24-hour period, while female partners desire sex most between 11 p.m. and 2 a.m.

Is one partner *right*? Is there an optimal time to have sex? In an attempt to puzzle it out, I look back at evolutionary biology.

“Early humans weren’t having sex at night until we discovered fire, about 1.6 million years ago,” says Helen Fisher, a biological anthropologist and senior researcher at the Kinsey Institute. According to her studies, ancient man actually had sex in the middle of the day: “They would wake up, eat, have sex, and then socialize.”

“Early humans weren’t having sex at night until we discovered fire, about 1.6 million years ago.” —Helen Fisher, biological anthropologist

As fun as that sounds, it wasn’t exactly an afternoon delight—the sole purpose of intercourse was procreation, and the constant threat of predators meant it had to be quick.

These days, we’re not constrained by the threat of a looming mastodon, and morning and night sex each boast some compelling benefits. AM sessions strengthen your immune system by ratcheting up your levels of IgA, an antibody that protects against infection, according to Debby Herbenick, PhD, a sex researcher and Indiana University professor. Obviously, this would come in handy for flu season.

On the other hand, both men and women experience an increase in prolactin, melatonin, and vasopressin after sex—all hormones that are linked to increased sleepiness. So if you have trouble falling asleep at night, sex might help—and conversely, if you have a hard time waking up in the morning, an early roll in the hay probably isn’t doing you any favors (unless you have the luxury of time to laze about while you recuperate).

It’s totally normal to have a night owl/morning person dynamic, and it doesn’t mean you’re sexually incompatible on a deeper level.

For the most part, though, the health benefits of sex, like mood-boosting dopamine, improved heart health, decreased stress, and stronger emotional bonds with your partner, apply to both AM and PM sessions. (Heyo!)

So the best time to have sex is really whatever the best time is for you and your partner. “Some people are talked and touched out at the end of the day,” says Shannon Chavez, PsyD, a clinical psychologist and licensed sex therapist. “Other people are finally decompressing from work and ready to relax and focus on sex.” It’s totally normal to have a night owl/morning person dynamic, adds Dr. Chavez, and it doesn’t mean you’re sexually incompatible on a deeper level.

Better yet, these peak desire times are usually malleable for both genders. One way to align your sex drives is a technique Dr. Chavez calls sexual conditioning. The idea is to find a time that works for both of you. (According to the Lovehoney study above, the second-most popular block of time to have sex—for both genders—is between 9 p.m. and 11 p.m., so that might be a good place to start.) The more often you have sex during this time, the more you’ll come to want sex at this time. “Positive sexual experiences that happened at night, or in the morning, or in a certain environment, will create a stronger arousal response in the future,” explains Chavez. You know what they say, practice makes perfect…

Originally published June 13, 2018; updated August 21, 2018.

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