The coronavirus pandemic and the anxieties it’s triggered have pretty much stolen my mojo. But pre-pandemic, evening sex, post-dinner and drinks, was absolutely my jam. My partner, on the other hand, was always more down to bone morning or night. I’ve been pondering the cause of my erstwhile evening horniness, and why the time of day didn’t matter as much for my partner. My bigger question: What determines whether you’re horny in the morning or at night?

It’s a tricky line of inquiry. The experts I interviewed say that the answer comes down to a complex combination of biological and environmental factors.

A 2014 study of 565 men and women in Poland suggests that biological sex and chronotype play a role. Your chronotype refers to variations in your wakefulness and activity throughout the day, per Healthline. In general, research groups people into three chronotypes: morning, evening, or neither.

In the Polish study, all the women, regardless of their chronotype, reported feeling horniest at night, although morning types reported a second spike between 6:00 and 9:00 a.m. All the men on the other hand, reported that their horniness peaked twice: once in the morning, and once at night — but in morning types, these peaks occurred earlier in the morning and night than in evening types.

Why were the men in the study, like my partner, down to pound, morning or night? In explaining their morning horniness, Konrad Jankowski of the University of Warsaw’s psychology department, the study’s lead author, pointed to men’s daily testosterone cycles, possibly tied to their circadian rhythms, or sleep-wake cycles. “The circadian peak of testosterone occurs in the morning,” he tells Mic.

In men (or anyone with a penis), “this can contribute to both morning wood and increased desire.” And according to evolutionary psychology, which posits that males are invested in sowing their sperm far and wide, “men need to be more flexible in case a mating opportunity arises.” (It’s worth noting, though, that the field of evolutionary psychology has often spurred controversy, and has also been used to justify sexism.)

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The reasons why men and women in the study reported feeling especially thirsty at night are probably largely environmental, Jankowski says. For starters, you tend to actually be with your partner in the evening. Drinking and dim lighting during these hours can lower your inhibitions. You also tend to socialize more, and worry less about work and other obligations.

“As we start to approach sleep, we get a slowing of brain activity, and that includes a rejection of cognitive control,” says Nicole Prause, a neuroscientist, researcher, and founder of sexual biotechnology company Liberos, who wasn't involved in the Polish study. High cognitive control — the alertness you feel while mentally reviewing your to-do list in the morning, for example — can make it hard to engage in sex.

Most of the participants in the Polish study were coupled up and living apart, or single; the vast majority were straight; and they all lived in Poland. That being said, we can't necessarily extend the findings on them to the general population, though they do provide food for though.

And Prause argues that your preferred time for sex might depend less on your sleep and hormone cycles and more on when you can get it. “We have some data saying the times people are more likely to want it are when they’re more likely to have it,” she says. That means if you work full-time, you’ll probably stick to weekends, and if you have kids, you’ll most likely work around their sleep schedule.

Your preferred time for sex might depend less on your sleep and hormone cycles and more on when you can get it.

Both Prause and Jankowski agree that not getting enough sleep can diminish your sex drive. (The Centers for Disease Control and Prevention recommends that adults ages 18 to 60 clock in at least seven hours a night.) Insufficient sleep not only saps you of energy, it also lowers testosterone and estrogen, hormones that play a major role in libido and sexual performance, Jankowski explains. And when you’re horny, your brain’s approach motivation network is active, Prause says, as it is anytime you’re motivated, whether to exercise or dive into a work project. Think of horniness as just another motivational drive; you’re less likely to feel motivated when you’re sleepy.

In other words, you tend to want to bang one out not only when you can, Prause explains, but when you feel especially motivated. If you want to go full-nerd, you can pinpoint this time by measuring your heart rate for a week with a fitness tracker. Maybe you see a spike every day at 3:00 p.m. or so, when you’re most active and walking around. “That’s probably a good time for you,” Prause says.

Think of horniness as just another motivational drive; you’re less likely to feel motivated when you’re sleepy.

If you're in a relationship, and you and bae prefer sex at different times of day, know that your experience is totally normal. Prause explains that discrepancy is the rule, not the exception. “It’s rare that people want to have the same frequency of sex at the same time,” she says. She suggests considering masturbation as a way to handle situations when one of you wants to have sex and the other doesn’t, and maybe talking about it in case you have different values around it within a relationship. (In some cases, if one partner masturbates, the other might view it as a sign that they’re “not enough.”)

Scheduling is another option. But rather than planning your sex sesh to the hour and framing it as the only time it can happen, ease off the pressure, and treat it as an experiment, Prause says. “We’re gonna lay in bed and snuggle,” she recommends telling yourselves. “If something happens, great. If not, then it doesn’t.” Try to find a time when you’re not causing or adding to each other’s fatigue. If anything, communicating and tuning into your sexual preferences in this way could strengthen your relationship, even if takes some time for you to get back in sync.