Most couples have sex at night. Comfortable, convenient, and according to one sleep expert, about the worst possible time your body could be doing it.

Clinical psychologist and sleep expert Dr. Michael Breus appeared on the Diary of a CEO podcast to make the case against late-night sex, and he came with data. According to a survey Breus conducted, most people are intimate between 10:30 and 11:30 pm, right before falling asleep. The timing makes intuitive sense. The biology, less so.

“In order to have successful sex, you want to have estrogen, testosterone, progesterone, adrenaline, and cortisol all to be high and melatonin to be low,” Breus explained on the podcast. By 11:30 pm, your body has done the opposite. Melatonin, the hormone your brain releases in the evening to prepare you for sleep, is surging. Everything else Breus mentioned is running low. “It’s literally the opposite—melatonin is high, and all those other things are low,” he said.

The Worst Time to Have Sex Is When Most Couples Are Doing It

The fix, according to Breus, is moving the whole thing to the morning. His reasoning is straightforward. “If you happen to be having sex with somebody who was born biologically male, what do most men wake up with? An erection. If that’s not Mother Nature telling you to use that thing, then I don’t know what is,” he said. The hormone profile in the morning is essentially everything late night isn’t, and Breus found through his surveys that people reported greater connection and performance when sex happened earlier in the day.

One small caveat. Breus isn’t suggesting you skip straight from REM sleep to the main event. He recommends brushing your teeth and adding some mouthwash first, calling what comes after the “perfect time” for intimacy.

He also touched on a separate sleep issue that affects more people than they’d probably admit. For anyone waking up between 1 am and 3 am feeling like they need the bathroom, Breus says, hold on. “Seventy percent of people sleep on their sides, and they are putting pressure on their bladder,” he said, recommending people roll onto their back and wait 25 seconds to see if the urge passes. Most of the time, it does.

And if you do have to get up, skip the overhead light and use a nightlight instead. Turning on a bright light tells your brain it’s morning and shuts down melatonin production entirely.

The body runs on a biological schedule. Most people just haven’t been paying attention to it.