It’s true, but it’s so not fair.

I’m ordinarily not one to cite my own, anecdotal experience as proof of a greater truth—okay, well, maybe I am.  But now actual research supports what I’ve experienced almost every night for the past eight years, and I’m feeling so vindicated that I’m going to share it with you.

Ladies, you know how it is.  You’ve made it through another day with too many temper-tantrums and not enough coffee.  You’ve finally made it to bed and fallen asleep.  You are OUT, and it’s good.

And then you hear a noise.  Maybe it’s a cry.  Maybe it’s a cough.  Or if you’re me and mother to a child like four-and-a-half year old “Emmie,” maybe it’s a string of incomprehensible words spoken in a tongue only known to residents of the Underworld and those they try to possess in their sleep.

Whatever it is, it’s coming from your child.  You hope that it’s part of your dream, but it continues and you have to admit to yourself that it’s real.  So you glance over at your spouse in the hopes that your partner in all things and at all times will volunteer to take this baby-call, but he is fast asleep.  For real.  That kid could be screaming right beside him like someone’s pulling off her toenails and he wouldn’t hear it.  So you curse your beloved and his ability to sleep soundly through his offspring’s cries, and you tend to your child yourself.  Then you can’t fall back asleep, and all the while, he’s slumbering, like, well, a baby (which, as an aside, is the most idiotic simile I think I’ve ever heard).

If this sounds like what goes on in your household, the good news is that you are not crazy.  The bad news is that apparently, these reactions are part of human genetic makeup, and there’s nothing we can do about it.

A study released late last year evaluated which sounds were most likely to wake men and women from sound sleep, and found that the triggers were different.  Women responded to babies’ cries, while men were more likely to awaken at the sounds of threats to the entire home and family, such as buzzing flies or windows rattled by the wind.  (Hey, I didn’t conduct this study.)  So as much as you might want to curse your partner at 3:00 a.m. for sleeping through yet another of the baby’s teething episodes or the preschooler’s nightmares, it really isn’t his fault.  (Note: this study was commissioned by Lemsip, a manufacturer of nighttime cold-and-flu medicine.)

Now before everyone goes crazy telling me about all of the exceptions out there: yes, I know.  There are exceptions to every rule, and some of you are my friends.  But this study doesn’t surprise me because I live it every night.  And now I can’t even get mad at my husband anymore because science says that he sleeps through the kids’ cries because of his biologically driven impulse to protect our family.  Way to go, science.

One more thing: it turns out that yup, women take longer to fall back asleep than men do.  Yeah, thanks, I knew that.  My husband can go through an entire REM cycle before I’ve even returned his “good night.”  I’m still working through a twelve-step program to learn how to forgive him for this.

So ladies, the next time you look at your partner slumbering peacefully beside you while your kid wails, don’t get mad at him.  It isn’t his fault.  As for you, gentlemen: remember that the decision of whether to get out of bed when your child cries at night rests with your partner.  Treat her well, or she will reach into her own evolutionary bag of tricks and find a way to make sure that you do wake up.  And it probably won’t be pretty.