Why Do Babies Smile In Their Sleep?

Why Do Babies Smile In Their Sleep?

Medically Reviewed By
Dr. Arti Sharma (Paediatrician)
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It is common for babies to smile or laugh when they are awake. But they also smile while sleeping. As they slumber in dreams, baby smiles emerge like magical whispers, revealing the purest expressions of their innocent joy. If you have recently given birth to your baby and watched him sleeping for hours, you must have noticed a twitch or smile on his face, and it must have been a sight to behold! But why does a baby smile while sleeping? Babies smile while sleeping because of reflexes, cognitive development, and emotional experiences. Read more to find out whether the baby is laughing or smiling in sleep.

Video: Why Do Babies Smile in Their Sleep?

Why Do Babies Smile or Laugh While Sleeping?

Many people think babies see angels while sleeping, which is why they smile. But that may not be true – as little scientific evidence is available. Babies are likely to smile or laugh in their sleep for one (or more) reasons.

Why Do Babies Smile or Laugh While Sleeping?

1. Developing Emotions

While awake, little ones are exposed to new sounds and sights. During this time, their developing brains may tend to record all the daily experiences and information coming their way, possibly getting processed while asleep. The happy emotions felt while dealing with the new knowledge and their understanding may be exhibited through smiles or laughter in their sleep. Hence, smiling or laughing while asleep can be a part of babies’ evolving emotions.

2. Passing Gas

Babies are believed to start displaying social smiles when they turn 34 months old. But if a baby smiles in the first few weeks of his birth, it may infer that he is probably passing gas. This notion is, however, not supported by any concrete scientific research. Nevertheless, it is a known fact that colic babies tend to remain irritable, and farting brings relief and helps them feel better. So one of the reasons for smiling during sleeping could be that the baby is passing gas.

3. REM Sleep Cycle

While in REM sleep, he can experience certain physiological changes that trigger some reflexes, including a smile. The REM sleep phase may also result in rapid eye movements (REMs) and vivid dreams. If you notice your baby smiling or laughing in his sleep, he may be in the REM sleep cycle, recalling some funny episode earlier in the day.

4. Other Medical Causes

In rare cases, convulsions and fits may manifest as unceasing laughter. If you notice other symptoms such as weight loss, trouble while sleeping, frequent bouts of irritability, or laughing for no apparent reason, you must immediately take him to a doctor. Convulsive laughter episodes can disrupt your baby’s resting schedule, thus negatively impacting his health.

How Can Sleep Cause a Baby to Smile?

Sleep holds many mysteries, and one of its delightful secrets is how it can cause babies to break into smiles. Let’s explore how sleep can evoke those precious grins in little ones.

1. Dreams and Imagery

During REM (rapid eye movement) sleep, the phase associated with dreaming, babies may encounter vivid images and experiences that evoke positive emotions, leading to spontaneous smiles.

2. Neurological Development

As babies grow and their brains develop, the neural pathways responsible for facial expressions become more active. Sleep allows these pathways to strengthen and refine, allowing spontaneous smiles to emerge.

3. Emotional Processing

Babies process emotions even during sleep. Positive emotions and experiences from the day can manifest as smiles while they slumber, reflecting their sense of contentment, happiness, or comfort.

4. Reflexes and Mimicry

Some smiles observed during sleep may be reflexive or mimicry of facial expressions observed while awake. Babies naturally mimic the facial gestures of those around them, and these mimicking behaviours can persist even during sleep, resulting in smiles.

Could a Baby’s Smile in Sleep Be a Cause of Concern?

A baby’s smile during sleep is generally considered normal and healthy behaviour. However, there are instances where it could be a cause for concern. It is important to note that these concerns are relatively rare but worth considering. Here are some factors to be aware of:

  • Muscular Twitching in REM Sleep: Babies spend significant time in REM (rapid eye movement) sleep, which is associated with dreams. During this phase, facial muscles may twitch and make involuntary movements, including smiling. These smiles are typically harmless and indicative of normal brain development.
  • Discomfort or Pain: Sometimes, a baby’s smile during sleep may be accompanied by signs of discomfort or pain. This could include facial grimacing, restlessness, or crying. If you notice these additional signs, it may be worth investigating further to determine if an underlying issue is causing distress.
  • Unusual Frequency or Duration: While occasional smiles during sleep are normal, excessive or prolonged smiling could cause concern. If a baby consistently exhibits a high frequency of smiles or if the smiles persist for unusually long periods, it may be worth discussing with a healthcare professional to rule out any underlying conditions.
  • Gelastic Seizure: A very uncommon type called a gelastic seizure can cause a person to laugh uncontrollably. One-third of those who suffer from these seizures had their first one as infants. Infants who are about to sleep can encounter gelastic seizures. If a newborn has a gelastic seizure while asleep, they may awaken and then go back asleep after the seizure. Gelastic seizures often last 10 to 20 seconds and can be accompanied by additional symptoms, including wriggling, moaning, lip-smacking, and laughter or smiling.

It is important to remember that every baby is unique, and individual circumstances may vary. If you have concerns about your baby’s well-being or development, it is always best to seek medical guidance from your paediatrician.

Different Types of Smiles in Infants

By now, you know why a baby smiles during sleeping. It could be due to developing emotions, the REM sleep cycle, or some medical issues. But did you know there are different types of smiles too? Yes, babies have different types of smiles, which have different meanings. And all these smiles are important milestones in their lives. If a newborn baby smiles in his sleep, his smile can be of three different types, and they mean the following:

1. Social Smile

Babies are likely to go through many emotional changes in the first few years of their life. As they slowly grow up, they may become more responsive, alert, and interact with other people. Babies between 3 and 4 months of age often break into social smiles as a reaction to the attention and gestures of the mother.

If your baby has developed a social smile, it is an important developmental milestone and indicates an intentional expression of warmth towards you. It means that your baby is bonding with you. When a baby shows a social smile, it could be a sign of brain development. It also means that the baby’s communication skills are advancing. At this point, you may want to interact even more with your baby by cuddling, making comical faces or even simply talking to him to increase more social smiles of your baby.

2. Reflexive Smile

Babies also demonstrate fleeting smiles while sleeping, especially within the first few days of birth. Experts believe these early smiles in babies are reflex actions similar to other reflexes shown by newborn babies, like sucking and rooting. Reflexive smiles while sleeping are supposed to be innate gestures. They do not have an emotional trigger but are usually nature’s way for a baby to begin practising different skills. Reflex smiles may happen while the baby is in his mother’s womb from 25 to 27 weeks of gestation. After birth, reflexive smiles may typically occur during the REM sleep phase.

3. Responsive Smile

Responsive smiles may manifest around 6 to 8 weeks after the baby’s birth. A responsive smile while sleeping may be a baby’s response to sensory experiences or things he finds enjoyable, like a familiar soothing voice, cuddles, etc. Responsive smiles are not social reactions but simply reciprocating actions subject to what a baby senses. Responsive smiles can help you learn about your baby’s likes and dislikes, what amuses him or what can make him grin. 


1. How to Encourage My Baby to Smile?

Encouraging your baby to smile can be a joyful experience. Here are a few tips to help stimulate those adorable little grins:

  • Face-to-Face Interaction: Make frequent eye contact, talk, sing, and make funny faces with your baby. Babies often respond to the attention and expressions of their caregivers, which can elicit smiles.
  • Gentle Touch and Tickling: Lightly tickling your baby’s belly or gently stroking their cheeks can trigger a positive response and possibly a smile.
  • Play and Toys: Introduce age-appropriate toys that stimulate your baby’s senses, such as colourful mobiles, rattles, or soft plush toys. These can capture their interest and potentially lead to smiles.
  • Peek-a-Boo: Playing peek-a-boo, where you cover your face and then reveal it, can be a delightful game for babies. The element of surprise and anticipation often brings about smiles and laughter.

2. Does My Baby See Angels When He/She Smiles in Their Sleep?

No, when babies smile in their sleep, it does not indicate seeing angels or any specific visual content. Babies go through different sleep stages associated with dreaming, including REM (rapid eye movement) sleep. Smiles during sleep are likely a result of their brain activity and emotional experiences during these dream-like states rather than visual perceptions of angels or other specific images. But apart from scientific evidence, it doesn’t hurt to imagine if babies see angels in their dreams!

Watching an infant smiling while sleeping is heart-warming and an important sign that the baby is developing emotionally and physically. Parents must understand that different babies have varied learning curves and developmental milestones. So they should not unnecessarily fret if their baby doesn’t display certain milestones. Let your baby develop at his own pace, and enjoy the little moments with him.


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Also Read:

Cute Baby Smiling Photos
When do Babies Smile Back?
Ways To Make Your Baby Laugh

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