Child Proof

The Scientific Cause of Sudden Toddler Meltdowns

Most parents think kids can control their emotions long before their brains are equipped to do so

Elizabeth Preston
Published in
4 min readApr 4, 2019


Credit: Malte Mueller/Getty Images

TToddler feelings come at you fast. One minute you and your child are having a joyful tickle-fest on the sofa; the next they’re lying on the floor and crying because you suggested wiping snot off their face.

As much as it may feel like your toddler is the world’s least rational human, there are scientific reasons for this unpredictability. Understanding what’s going on in your kid’s head can help you teach them to handle their feelings—or, at the very least, keep you from ending up crying on the floor yourself.

Around age two, kids’ personalities are blossoming, says Rebecca Parlakian, parenting expert for the nonprofit Zero to Three. Two-year-olds are funny and charming and may express themselves well verbally. The downside of this is that they kind of fool us into thinking they’re more mature than they really are, Parlakian says.

That’s because the toddler brain is changing in major ways during early childhood, says Mary Margaret Gleason, a pediatrician and child psychiatrist at Tulane University. It’s sprouting new connections between brain cells at an astonishing rate, and it is beginning to prune back unnecessary connections. And the prefrontal cortex, the brain area behind the forehead that helps with planning and other tricky cognitive tasks, is nowhere near complete. In fact, it keeps maturing into early adulthood.

Among the critical skills a young prefrontal cortex hasn’t yet mastered is self-regulation, or the ability to control emotions and behavior. This is what helps transform a volatile toddler into a kid who can keep their cool when they find out their favorite pajamas are in the laundry. Carol Weitzman, a developmental-behavioral pediatrician and professor of pediatrics at the Yale School of Medicine, says that when parents and doctors talk about developmental milestones, they should really be talking about milestones of self-regulation too.

But while a toddler’s brain is still building the areas that will let them control their feelings, their sense of self is also emerging. At age two, they know…



Elizabeth Preston
Writer for

Elizabeth Preston is a freelance science journalist and humor writer in the Boston area.