It is common to see babies smile, laugh and giggle while awake. It makes for a really happy sight! When they smile in their sleep, it makes them appear more like angels in a crib. 

The fact is that babies smiling or laughing in their sleep is cute and makes parents reach out for their camera.

But why do babies smile in their sleep? Let's explore the physiology behind this gorgeous reaction...

Understanding The Effect Of Sleep Cycles On Your Baby

The first step in understanding why babies smile during sleep is exploring the concept of sleep. 

There are two main types of sleep - Rapid Eye Movement (REM) and non-REM sleep. 

Let’s begin with non-REM sleep. Basically, non-REM sleep is divided into three stages. 

During stage one, your body moves from being vividly awake to being partially asleep. Here, your breathing slows down; and so does your brain waves. 

In Stage two, you experience a period of light sleep - your heart and breathing rates slow more while your muscles relax. 

The last stage is necessary in order to feel refreshed when you wake up. At this point, your heart and breathing rate, as well as your brain waves are at the slowest point.

In REM sleep, you begin to dream. This is often accompanied with temporary paralysis of your arms and legs. As the name suggests, your eyes move quickly back and forth under your eyelid. Also, your breathing is sporadic however, your heart beat and blood pressure is similar to when you are awake. 

It's in this stage that your baby is more likely to smile. Laughing in sleep is most common in the REM stage.

Although, it is impossible to tell whether babies dream or not, we do know for sure that they experience the equivalent of REM sleep called active sleep. When babies smile during their sleep, it is often considered to be a reflex rather than an end result of a dream they are having. During this active sleep, they experience some physiological changes resulting in the trigger reflexes and one of them could be a smile. 

Baby Sleep Consultant Sydney can be of immense help in giving you a breakdown on what goes on in your baby’s mind while asleep and can also assist with age-appropriate sleep guidelines. 

Developing Emotions

Another reason babies smile during sleep is due to their developing brains. While they are awake, your little one observes the world around them.  They are exposed to new sounds, sights and a plethora of emotions. 

It can be impossible for their developing brains to record all the information coming its way. So, the brain may tend to record these events and process them while they are asleep. The happy emotions felt while dealing with these memories might just result in a smile. Your baby might be recalling a funny episode observed during the day. Who knows?

Final Words

While there are rare occurrences when smiling in sleep could indicate sleep disorders, it is a generally harmless happening. You have nothing to worry about, so enjoy the smiles.