Why Do Babies Smile In Their Sleep?

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It’s a question that has puzzled parents for centuries: Why do babies smile in their sleep? Some say it’s because they’re dreaming, while others believe it’s a reflex. Well, Baby smiles are beautiful, mysterious, and special. If you have these or more related questions, you have come to the right place. Herein, we’ll explore why newborn babies smile in their sleep and how parents should respond.

What Are the Possible Reasons Why Babies Smile in Their Sleep?

There are several reasons why babies smile in their sleep. Here are some common ones.

Reflex Smiles

Babies’ smiles in their sleep may be one of the most captivating sights that cause adults to marvel at their innocence and beauty. While some might view these nighttime displays of happiness as random acts, studies have shown that young infants smile for several reasons, one of which is reflexes.

Primitive reflexes such as the ”Moro reflex” are typically experienced in newborns between one month to six months old. They are triggered by a sudden movement like a baby feels like it’s falling or a slight jolt. The involuntary reaction consists of the infant extending its arms forward, then upward and back towards itself, while simultaneously crying out or giving a faint smile. Though usually not something intentional, sleeping babies may give off broad early smiles if they experience something that provokes this reflex!

REM Sleep

why do babies smile in their sleep Studies have overwhelmingly shown the importance of REM sleep for developing babies. REM sleep, or Rapid Eye Movement, is a stage during which the body is most relaxed, and dreaming can occur. Like adults, infants need REM sleep to develop brains capable of remaining attentive and quickly remembering information. Babies acquire approximately half of their total sleep time in the REM stage each night, and this period increases in frequency with age.

It has been observed that infants usually spend more time in non-REM sleep than an adult, but it is important to note that the amount spent in REM sleep is relatively higher than that seen by adults at 36 weeks gestation age. Without sufficient REM rest, babies may face issues with attention or struggle to store new data in their young brains. Therefore, ensuring babies get enough restful nights will make their mental development optimal as they grow up.


One of the most popular theories behind baby smiles is that they result from dreaming. When babies snooze and enter REM sleep, it’s thought that their brains travel to places unknown with their imaginations and thus produce sweet dreams. Babies’ dreams can be both positive and negative; if they happen to be positive, this could explain why some sleeping infants give out those tiny, cute grins.

Social Smiles

why do babies smile in their sleep

It’s also possible that infants can smile socially, even from a very young age. Babies may recognize their parent’s voice or presence and react with an involuntary facial expression indicating approval. As babies grow older, these social smiles become more recognizable and intentional.

Other Reasons

Besides reflexes and dreams, there are other reasons babies may smile in their sleep. Some believe these expressions of joy occur when babies recognize the sound of their parent’s voices or feel safe and secure in the comfort of familiar surroundings. Other possible explanations include hunger pangs or simply

How Should Parents Respond?

When your baby smiles in its sleep, it can be both wonderful and worrying; after all, you don’t want anything bad happening to your precious little one! While smiling in their sleep is usually nothing to worry about, it’s still important for parents to be aware of their baby’s sleeping habits. If you notice any changes in your baby’s behavior or your infant seems unusually fussy and often wakes during the night, it could be a sign that something is up. Consulting a doctor would then be recommended to ensure everything is alright.

How to Make Your Baby Smile?

Sometimes, the most difficult part about getting your baby to smile is simply trying to engage them. The following tips can help:

  • Talk to your baby often and use a high-pitched “baby talk” voice: Babies are known to respond well to this tone!
  • Sing nursery rhymes or children’s songs are soothing for babies and may even make them giggle.
  • Read books with your infant: Whether it be stories, poems, or simple picture books- together is a great bonding activity that could get those adorable smiles out of them!
  • Play peek-a-boo: Playing games like this helps create positive associations between yourself and the baby, and it’s also a great way to get them laughing.
  • Get silly! Show your baby funny faces or make up goofy noises; these can bring a smile to anyone’s face, even babies!
  • Make their bassinet Comfortable: Ensuring your baby has all the comforts they need to rest peacefully, can be a great way to ensure they get the active sleep they need! A sizeable and comfy bassinet can play the trick.

Stages of Sleep Babies Experience

why do babies smile in their sleep

Sleep is an incredibly important part of life, and the process of sleep helps a baby’s physical, mental and emotional development. It can be challenging for parents to understand what stages of sleep their babies go through, so it’s helpful to have an overview of the basics. Generally speaking, newborns will cycle between light and deep sleep within their naps every one to four hours.

As they grow older, babies spend more time in a single REM or non-REM (deep) stage during naps, usually going into non-REM sleep first, followed by one or two REM stages with some light wakefulness in between each cycle. Most infants three months and older will transition into one long stretch of about seven to nine hours of good sleep in their bassinet at night. That includes light and deep sleep with brief periods of wakefulness during which the baby is quiet and close to falling back asleep unless disturbed. Understanding how different stages of sleep work together helps ensure your baby sleeps well and gets the rest they need for healthy growth and development.


Infant smiling in one’s sleep isn’t something that should concern parents unduly, but it is important to remain vigilant regarding your baby’s health and well-being. Babies’ smiles are usually just a result of reflexes, REM sleep, dreams, or social recognition — all signs of progress and development! So, take some time every day to appreciate those sweet sleeping smiles!

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Jenny Chaines

Jenny Chaines

Having the perfect bassinet is something that every mother wants for her child.
I've been doing my own due diligence since the day I knew I was pregnant and I'm here to let you in on the ins and outs of it all...

About Me

Having the perfect bassinet is something that every mother wants for her child.
I’ve been doing my own due diligence since the day I knew I was pregnant and I’m here to let you in on the ins and outs of it all…

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