Other kids shrieking their lungs out has little impact on me—if I see the parent has things under control, I carry on with my day. But when my baby cries? The sound is unbearable. Like a corkscrew twisting in my chest with increasing maliciousness until I swoop in for a cuddle, determine the cause, and all is right with the world again. Turns out, I’m not an overly-anxious, mildly unhinged mum—the maternal discomfort wrought by a child’s tears is a universal, physiological phenomenon, provable by science.
A study of mother mice revealed that by introducing oxytocin (the hormone released in copious amounts during labour and lactation) to the mama brains, their responses to the sound of their crying pups was significantly fine-tuned.
The conclusion was that this “motherhood hormone” appears to ramp up sensitivity to the sound of your baby in need, creating a sense of urgency. Robert Froemke, the study’s senior investigator, explains that oxytocin likely “amplifies the way the auditory cortex processes incoming cries from our own babies”.
The reason is clearly part of a survival mechanism, prompting parents to tend to their children’s immediate needs. Over time, the sound of crying may not be as stressful to your ears, once you learn to recognise what each type of cry means, and how best to respond.
Even more interesting, mothers’ brains are far more attuned to their crying offspring—which is why dads can sleep through the noise.
Froemke notes that extra oxytocin does not manipulate a reaction to crying pups in male mice quite like it does in females.
“There is a difference in terms of sensitivity to oxytocin. We think that may be because the male oxytocin system is already maxed out,” he says. Still—Froemke adds that when mouse fathers co-habit with females and young ones, their oxytocin levels can increase.
So…dads aren’t quite off the hook when it comes to the 2am shift. Even if you have to bring baby closer to their ears to help them along.