Why Do Babies Smile in Their Sleep?

It can be awfully cute when babies smile in their sleep—but is it a real smile, or just a reflex? We turned to experts to learn more.

Among all of your baby’s first milestones, smiling is arguably one of the cutest! While you eagerly await that first gummy grin, your baby may surprise you by offering up a little smile while they’re asleep, even in the first few weeks following birth.

So why, exactly, do babies smile in their sleep? Is it intentional, or something else? Here, we’ll take a look at the possible reasons, what a newborn’s sleep pattern looks like, and how to encourage your baby’s smile when they're awake, too.

Baby Smiling in Sleep: Reflex or Genuine?

While adorable, your baby’s sleepy smile is likely the result of an involuntary reflex. “Babies can make very expressive faces during different sleep stages. It’s not unusual to notice a baby’s seemingly first smile while they are asleep,” explains Amaka Priest, M.D., a pediatrician and member of Swehl's Motherboard, the brand's panel of advisors made up of doctors, doulas, and lactation experts. “Interestingly enough, babies might also frown, twitch, smack, or suck their lips while asleep as well.”

These sleep reflexes may serve as “practice” for your baby, helping them master future social skills. “Studies suggest these movements may strengthen the muscles a baby will intentionally use to smile and to make other facial expressions as they age,” says Dr. Priest.