What Makes Babies Smile in Their Sleep?

Published: Dec 21, 2020
Updated: Oct 14, 2024
What Makes Babies Smile in Their Sleep?
In this article
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    9 min

    Have you ever wondered why babies smile in their sleep? It’s a fascinating phenomenon that has puzzled parents for generations.

    In this article, we’ll explore the science behind those adorable newborn baby smiles. From the different stages of sleep to the development of smiling muscles, we’ll uncover the secrets behind this heartwarming behavior.

    Plus, we’ll discuss how baby smiles promote social connections and better sleep. So, if you’re curious to understand what makes your little one smile during dreamland, keep reading.

    Key Takeaways
    Babies may smile during sleep, particularly during rapid eye movement (REM) sleep.
    Infant smiling while sleeping may help develop the muscles used for smiling.
    Newborn smiles may vary depending on the baby’s age and sleep stage.
    Smiling in babies is related to sleep and can contribute to better sleep quality.

    Why Do Babies Smile In Their Sleep?

    ShutEye why do babies smile while sleeping reasons

    There are three main reasons why babies smile in their sleep.

    First, smiles in babies are reflex actions similar to sneezing and coughing when something irritates your nasal passages. Baby’s first smile is usually a reflex smile, which is a spontaneous movement of the facial muscles. This reflex smile isn’t a reaction to any external stimulus but rather a result of the baby’s developing nervous system.

    Second, babies smile and laugh while sleeping as a response to pleasant dreams or positive experiences they’ve had while awake. These smiles can be seen as a reflection of their emotional state during sleep.

    Lastly, little smiles during sleep may simply be a result of the baby’s brain activity, as they enter the rapid eye movement (REM) stage of sleep. During REM sleep phase, the brain is highly active, and this increased brain activity may trigger involuntary sleep smiles in babies. These smiles are not social reactions, they are just a sign that your baby has gone through the deepest of NREM sleep to the REM phase. 

    Is it normal for babies to smile or laugh while asleep?
    Yes, it is entirely normal for babies to smile or laugh while babies dream. These spontaneous expressions are part of their healthy sleep habits and indicate their overall contentment and well-being during their slumber.
    Dr. Wei Cui
    Internal Medicine Physician and Applied Psychologist

    Sleep Stages and Smiling

    ShutEye babies sleep stages and smiling

    As you enter the realm of sleep and its stages, you may wonder how these stages contribute to the adorable phenomenon of babies smiling in their slumber. The answer lies in the REM sleep cycle, or rapid eye movement sleep, which is when dreams occur. Here’s how the sleep stages and smiling connect:

    • REM sleep: This is the stage in which babies smile during sleep. It’s a light sleep stage where dreams occur, and the brain activity is similar to when we’re awake.
    • Sleep cycle: Babies sleep in cycles, with REM sleep occurring episodically between the stages of NREM sleep.
    • Social smile: The smiles that babies display during sleep are believed to be reflex smiles, laying the groundwork for genuine smiles as they grow.

    Understanding these sleep stages helps explain babies’ reasons for smiling during sleep, adding to their overall cuteness factor.

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    Differentiating Reflex-like Smiles and Genuine Smiles

    To understand the distinction between reflex-like smiles and genuine smiles in babies, it’s important to explore the underlying factors that contribute to these different types of smiles.

    Reflex-like smiles are often seen in newborns and are considered more involuntary responses to internal physical feelings, such as gas or hunger. These smiles aren’t necessarily indicative of the baby’s emotions or cognitive development.

    On the other hand, genuine smiles, also known as social smiles, are more deliberate and are believed to be generated in the cerebral cortex. Genuine smiles during sleep may indicate more advanced cognitive development.

    It’s fascinating to observe the different types of smiles that babies display, both while they’re awake and during their peaceful slumber.

    Concerns Related to Baby’s Smile or Laugh

    If you have any concerns about your baby’s smile or laugh, it’s important to address them and seek guidance from a healthcare professional.

    Some concerns related to your baby’s smile or laugh during sleep may include:

    • Gelastic seizures: These rare seizures can cause uncontrollable laughter in infants, even during sleep. They’re usually short in duration and not accompanied by amusement.
    • Sleep disturbances: If your baby’s smile or laugh during sleep is disrupting their sleep patterns or causing them to wake up frequently, it may be a cause for concern.
    • Emotional development: If you notice a lack of smiles or laughter during sleep or awake periods, it may be worth discussing with a healthcare professional to ensure your baby’s emotional development is on track.
    Should I be concerned if my baby smiles or laughs too much while sleeping?
    There is generally no cause for concern if your baby smiles or laughs frequently while sleeping. It’s considered a natural and adorable part of their sleep behavior. However, if you have any specific concerns about your baby’s sleep habits, it’s always best to consult with your pediatrician.
    Dr. Wei Cui
    Internal Medicine Physician and Applied Psychologist

    Importance of Baby Smiles

    The significance of baby smiles lies in their ability to foster positive emotional connections and facilitate bonding between infants and their caregivers. When a baby starts smiling, whether it’s during sleep or while awake, it brings joy and happiness to those around them. Smiles in babies aren’t only adorable, but they also serve as a way for infants to communicate their contentment and satisfaction.

    The early smiles in babies, including those during sleep, can create a strong bond between the baby and their caregivers. It’s a way for the baby to express their trust and reliance on their caregivers, and for the caregivers to feel a deep connection and love for the baby.

    These smiles in babies are an essential part of their emotional development and contribute to their overall well-being.

    Encouraging Baby to Smile

    Encouraging your baby to smile can be a delightful and rewarding experience for both you and your little one. Here are some tips to help you bring out those adorable smiles:

    • Engage in face-to-face interactions with the baby, making eye contact and smiling yourself.
    • Use gentle touch and tickling to elicit a smile.
    • Play games like peek-a-boo or make funny faces to create surprise and excitement.

    By incorporating these activities into your interactions with your baby, you can create a positive and joyful environment that encourages your baby to smile and laugh.

    Conclusion

    There are two states of deep sleep and light sleep in babies’ dreams. A newborn’s sleep cycle is only one hour. When a cycle is over, if the baby is not hungry or does not want to go to the toilet, it will enter the next sleep cycle.

    During the sleep cycle, there are two sleep states, deep and shallow. When the baby enters the light sleep state, various expressions will appear on the face and even make sounds.

    There are many baby sleep apps out there, but if you want the most comprehensive and most detailed (not to mention most popular) option for new moms & dads, check out ShutEye.

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    FAQ

    The smiles that babies have while sleeping are usually reflexive and spontaneous. These smiles are not in response to external stimuli, but rather appear to be a result of their dream experiences or simply a reflection of their inner contentment and comfort during sleep.

    Yes, babies can also laugh in their sleep, especially during the REM phase of sleep. It's a heartwarming sight for parents to witness, and it's another indication of the positive and peaceful internal experiences that babies may have during their sleep.

    A baby's smile during sleep is often connected to the REM (rapid eye movement) phase, where dreams and positive sensations can lead to a smile. Additionally, the overall comfort and peace that a baby experiences during sleep also contribute to these spontaneous smiles, making their sleep an adorable and serene experience.
    About authors
    Jessica Brown, a 29-year-old freelance copywriter passionate about human nature and deeply committed to promoting sleep and mental health awareness. Jessica holds a Master of Arts in Literary Studies from the National University of Singapore and a Bachelor's in Biology from the University of Cambridge.
    Dr. Wei Cui
    Reviewer
    Dr. Cui is a board-certified internal medicine physician and applied psychologist with more than 30 years of experience in both fields especially in terms of the regulation and intervention of sleep disorders.