The Surprising Reason Babies Cry at Night

A new study speculates on an interesting reason babies cry at night—it could be because they’re trying to prevent Mom from procreating and giving birth to a sibling. Sneaky!

The research, published in the journal Evolution, Medicine, and Public Health, hypothesizes that whether consciously or unconsciously, babies could be applying a “survival of the fittest” technique, preventing the birth of a new sibling that will compete for food and care from their mother.

“It’s clear that babies can get enough milk even if they sleep through the night,” evolutionary biologist David Haig told NPR. “The waking becomes a different issue. I’m just suggesting that offspring have evolved to use waking up mothers and suckling more intensely to delay the birth of another sibling.” Nursing a child, especially at night, can stop women from resuming ovulation soon after a pregnancy, explains NPR. By keeping Mom too tired to procreate, the baby guarantees that he or she won’t have to share her resources.

Not everyone agrees with Haig—it’s not just the baby who benefits from nighttime feeding, anthropologist Holly Dunsworth tells NPR. “There are so many good juices running through infant and mom,. It’s rewarding beyond the calories and hunger satiation for everyone involved. When you look at it from that perspective, waking up to feed looks more like cooperation than conflict.”

What’s in Your Baby’s Toothpaste?


Sarah Crockett
Sarah Crockett4 years ago

Thanks. I never thought of this as a reason.

Christine Jones
Christine J4 years ago

Not the only reason they cry, but it does make sense.

Julianna D.
Juliana D4 years ago

Both ideas could be correct.

Krista Slavin
Krista Slavin5 years ago

Idon't believe it.

Anne K.
Anne K5 years ago

Thank you!

Catrin K.

Have animals so i will sleep well at night without any crying :) !

Rose Roma
R. R5 years ago

Bravo, Sheila & Kathrynelizabet! Speak out about non-articles and BLUR "journalism". Both of you educated and reasonable. For info -- waste of time. For joy at readers' response -- worth my time to read. Since you are located
opposite sides of USA, I am hopeful about our nation now. Thanks, again.

Sheila Swan L.
Sheila Swan L5 years ago

I think this may be a theory that's an evolutionary stab in the dark, so to speak. Really, there are a lot of reasons babies wake in the night and this may be one but any mother knows that a baby could be wet or cold or even have a dream that isn't dreamy. They can't speak so what else would they do for attention than cry or make enough noise for their mothers to comfort them.

Christine W.
Christine W5 years ago

Thanks for sharing.