Why do Babies Smile in Their Sleep? | Let’s Find Out

When you have a newborn baby, you’ll often find yourself standing over their crib, gazing at them in awe as they sleep soundly. Whether this is because you’re finally getting a minute’s peace or because you look like a sleeping angel has a lot to be said for. Especially if your baby has been fighting sleep for the last few nights.

However, sometimes while watching your baby drifting through slumberland, you will notice that a slight smile washes over their face. There is always that one relative who says, “it’s just gas.”

Is this the case, though?

There are numerous reasons for your baby to smile in their sleep. Contrary to popular belief, sometimes it can be a smile caused by a feeling or emotion.

Sleeping babies may smile for circumstances such as developmental, response, or simply because they’re passing through certain sleep stages, such as R.E.M. sleep.

In some rare cases, babies smiling while they are asleep can be a cause of an underlying condition, which would require an investigation by their pediatrician. However, other symptoms will usually accompany these issues, so try not to let this worry you. If your baby smiles while sleeping, chances are, it’s nothing to be concerned about.

Throughout this composition, I will inform you about the many possible reasons for your baby smiling. At the same time, when they’re asleep, you will already be aware of some of which you may never have even considered.

So, if you’re curious about what causes your baby to smile while asleep, read on to understand the possible explanations.

R.E.M. Sleep And Other Sleep Stages

R.E.M. Sleep And Other Sleep Stages

As I mentioned, sometimes your baby smiles in their sleep because they are passing through a particular sleep stage. Like adults, babies also go through R.E.M. sleep (rapid eye movement) and NREM (non-rapid eye movement).

The NREM sleep stage happens when your baby first falls asleep. At this point, your baby begins nodding off and drifting into sleep. During this stage, you will notice their breathing becomes slower, and they can be easily awoken. So, this is the point at which parents will need to be as calm and quiet as possible.

The next period of sleep is what’s known as light sleep, where the muscles, heart, and brain slow right down, with only small bursts of activity.

After reaching the deepest level of NREM sleep, in which your baby will not move. Their breathing will be at its slowest; they will then slip into R.E.M. sleep when they are most likely to dream, as their brains become active. During this stage, it’s normal to see reactions such as twitching, eye movement, and even smiling.

Why is Your Baby Smiling While Sleeping?

Why is Your Baby Smiling While Sleeping

Aside from smiling due to their stage of sleep, many other environmental and physical circumstances could cause your baby to smile while they sleep, so let’s look at them in a bit more detail.

1. Passing Gas

Passing Gas

As I said in the intro, one of the first responses you get from people when your baby smiles in their sleep are that they could be simply passing gas. Although it’s nice to think your baby is dreaming of sweet nothings and making them smile, it is actually possible that the wind could cause the smirk.

Although it hasn’t been scientifically proven, it is highly likely that a baby feels a sensation of pleasing relief when they pass gas. After all, a baby with gas is uncomfortable and antsy, so yes, on occasion, your baby could smile in their sleep because they have just relieved themselves of unwanted gas.

2. Emotional


When your baby reaches about three months old, they will start to experience emotions other than crying because they are hungry or uncomfortable. They will begin to recognize a feeling of happiness when they see you or hear your voice, and this can also happen when they’re sleeping; your presence in the room can cause your baby to let out a small smile, even while drifting off to sleep.

3. Dreaming


While your baby sleeps, it is unlikely that they are having any form of a dream. This is because, as adults, while we sleep, our brains make up scenarios based on knowledge, memory, and past experiences. Of course, a baby doesn’t have any of these yet.

So, when you see your baby smiling or giggling while they’re asleep, it is likely to be that the brain is reacting to a feeling or emotion that they’re experiencing during R.E.M. sleep.

4. Responsive


When your baby is approaching two months old, they will start to have sensory responses to certain feelings and experiences they enjoy, such as tickles, cuddles, and the sight of their parents.

This means that while they are sleeping, they may also feel occurrences that cause them to smile. Such as the feel of a blanket or the comfort of a bed.

5. Reflex


I mentioned earlier about babies smiling during R.E.M. because their bodies are experiencing muscle reflexes. This means the smile isn’t coming from any stimulation, feeling, or experience. But in fact, it’s coming from muscle reflexes. This is the same as when you see your baby making a sucking motion while they’re asleep.

In concept, it’s the baby’s body’s way of learning movement and life skills. Reflex smiles are believed to start as early as when the baby is still in the mother’s womb.

6. Medical Conditions

Medical Conditions

In rare cases, smiling or excessive laughing can indicate an underlying health condition. If your baby’s slumber smile is happening in-frequently, and everything seems fine, then it’s likely nothing to worry about.

However, in the case that your baby is showing other symptoms such as weight loss, fighting sleep, random bursts of laughter, or restlessness, then it’s recommended to see a pediatrician to rule out anything more sinister.

The same goes for if your baby never smiles at all, so if by the time they’re around three months old, you’ve still never seen them express a smile, this could also be worth checking out to rule out any developmental problems.

Key Points

I think everyone can agree that watching a sleeping baby is both touching and magical. It is also a comforting sign that your baby is developing the specific skills they’ll need as they grow out of the newborn stage.

However, it’s important to remember that no two babies are the same, and while some may be full of emotional and reactive smiles, others may not. So, it’s vital to keep a close eye on your baby’s development and seek advice from a medical professional if there is anything concerning you.

So, the next time someone tells you that your baby is only smiling in their sleep because of their passing gas and bursts your new parent bubble, you can tell them that this might not be the case. Ok, so the likeness is that they aren’t smiling because they’re dreaming about cuddles and teddy bears, but still, there are plenty of other reasons that could be causing your smiling baby to share a smirk.

No matter what the cause of your baby’s sleep smiling, 99% of the time, it’s completely normal, and it only means that their little brains and bodies are developing just as they should. As long as your baby isn’t experiencing any discomfort, you can continue cooing over your sleepy, smiling little person.

Sarah Wagner

I'm Sarah Wagner, and I founded Sweet Island Dreams in 2022. It's a blog dedicated to helping people mental vacation virtually anytime they want. By providing information about the best sleep of your life, I help people drift away to paradise without ever having to leave their bed!