By Alanna Nuñez
June 28, 2013

Sometimes the things researchers study are baffling. Take, for example, a 2005 study that people have been talking about again recently that examined why we have sex at night.

If you're thinking to yourself, "Maybe it's because my day begins at 5:30 with a workout and a commute, and I barely have time to take a lunch break, let alone race home to get it on and be back to the office by 2, and also, telling my boss that I have to leave so that I can go have sex is generally frowned upon in polite society," then you'd be right!

Robert Refinetti of the University of South Carolina looked at a 1982 study published in Human Biology by researchers John Palmer, Richard Udry, and Naomi Morris that studied 78 married couples and found that they had a "large copulatory rate" during the weekdays. Curious, he wanted to see if he could replicate the results, as well as see if any environmental, biological, or cultural factors played a role in why people choose to have sex more around bedtime than any other time of day.

Using a sample of people with a wider age range than the original study, Refinetti determined that most people choose to twist the sheets most often at night for a few reasons: It's convenient (you're most likely already in bed with your S.O., so why not?), it's socially conventional (i.e. getting freaky in bed at midnight might annoy your neighbors upstairs, but it's not totally out of line, whereas getting freaky at 2 p.m. near an elementary school will probably get you arrested), and it could be an "emergent feature of our social structure" (most likely, you're not having sex as you drive home from work or make dinner).

These reasons all make a lot of sense. After all, there are only so many hours in a day, and most people follow a 9-to-5-type schedule that makes it hard to sneak away for a spontaneous bit of afternoon delight. However, a biological explanation could also exist, Refinetti told i09. "I would expect the effect of circadian rhythmicity on sexual desire to be weak. To study it, we'd have to keep couples alone in constant darkness for many days and check when they initiate sex," he says.

We're sure they can find volunteers for that.