Housework After Sex, Not Sleep


Hold on to your seatbelt for this one.

Professor Elwyn Isaac from England's University of Leeds has just discovered an astonishing behavior among fruit flies: after mating, females ditch their usual afternoon siesta in favor of engaging in intense foraging (ahem, that would be akin to domestic-type duties or housework).

The trigger? A "sex peptide" that is produced in the males' accessory gland, the equivalent of the human prostate, and attaches itself to the surface of the sperm's tail.

This sex peptides appears to have a chemical effect on the female, preventing her from taking her usual afternoon nap. This suggest the behavioral change has a purpose: to prepare females for the birth of offspring, and ensure successful paternity after mating.

Okay, so maybe you're not so impressed about new tidbit about how the fruit fly -- that buggy nuisance you see on rotting fruit and vegetables -- mates and changes behavior. But fruit flies, if you recall from high school biology days, have been the center of attention in research circles for decades. For starters, the fruit fly's genome has been fully mapped, so wide ranging genetic studies are possible. In terms of sleep studies:

  • They provide a good model for examining sleep behavior because they exhibit many of the hallmarks of mammalian sleep.
  • Like (most of) us, they sleep deeply at night from which they're difficult to rouse and they have a preferred sleeping posture. They also enjoy afternoon naps.
  • If they are sleep deprived, they show tiredness the next day.
  • If fed caffeine, they stay awake, and they become drowsy if given antihistamines.

Women can rest easy. I don't think human sperm contains a similar sex peptide that inhibits sleep and triggers them to spring into household action. (Though many women do feel energized after sex and can be known to get up and go as compared to their male, sleepy counterparts.) Human females have a long nine months during which they can prepare for birth.

But I wonder, are there ingredients in human sperm yet to be identified that can chemically alter a woman's body? Help her to conceive? Prepare the body for pregnancy? A lot of research in the past decade has focused on estrogen's role in sperm (yes, men do produce estrogen, and lots of it in sperm). So I don't doubt we'll learn more with closer inspection. Fruit flies and all (let's not forget about the mice, too).

Sweet Dreams,

Michael J. Breus, PhD

The Sleep Doctor™

This article about sex and sleep is also available at Dr. Breus's official blog, The Insomnia Blog.