Why Do Babies Cry in Their Sleep?

Ever watched your peacefully sleeping baby suddenly let out a tiny wail – then drift right back into dreamland as if nothing happened?

It’s enough to leave any parent wondering: Was that a nightmare? Are they in pain? Should I intervene?

The good news is that in most cases, those sleepy tears are a normal part of your baby’s development. In this blog, we’ll explore why babies cry in their sleep, when to check on them and how to create a calming sleep environment that supports your little one through every whimper, wiggle and wonder-filled dream. (So you can sleep better, too, parents.)

Yes – completely normal.

Newborns and young infants have very different sleep cycles compared to adults. They spend more time in active sleep (similar to REM sleep), which is a lighter stage of sleep where brain activity is high and physical movement is common. During this time, babies may grunt, twitch, flail their arms or even let out a brief cry without fully waking up.

Unlike adults, babies are still learning how to transition smoothly between sleep stages. As a result, they may cry out during these transitions, especially as their developing nervous systems process new sensations and experiences, even in sleep.

While it can be jarring to hear, crying during sleep is often just part of your baby’s natural development. Here are some of the most common causes behind those nighttime tears.

Like we said, babies spend a significant portion of their sleep in a light, active stage. During this phase, it’s normal to see rapid eye movement, fluttering eyelids, squirming or brief cries. These noises don’t always mean your baby is fully awake or upset – they’re often just signs of a busy brain at work.

The Moro reflex is an involuntary protective motor response against abrupt disruption of body balance or extremely sudden stimulation. Especially common in the first few months, the Moro reflex can cause your baby to suddenly flail their arms or legs and cry out. It’s a normal reflexive response to feeling like they’re falling – and one that typically fades by 3 to 6 months of age.

Babies, especially newborns, have tiny tummies and need to feed frequently – even during the night. A sleepy cry may simply be their early signal that it’s time to eat, even if they’re not fully awake yet.

Gas bubbles, reflux or the need to burp can all lead to brief nighttime fussiness. Since babies are still developing their digestive systems, it’s not uncommon for them to squirm and cry in their sleep until the discomfort passes.

As babies grow, teething can introduce new sensations like gum pain or ear pressure that cause intermittent crying during sleep. If your baby seems more restless than usual, check for other symptoms like a mild fever or congestion.

Around 6 months and beyond, babies begin to develop a deeper awareness of their surroundings – and of your presence. Even in their sleep, they may cry out during moments of transition or uncertainty, especially if they briefly stir and realize you're not right there.

It’s natural to want to swoop in at the first sign of a cry, but sometimes, a little patience can go a long way.

Many babies cry briefly in their sleep without fully waking up. In these cases, jumping in too quickly can accidentally rouse them from a natural transition between sleep cycles. If your baby seems otherwise settled – eyes closed, breathing steady, movements minimal – it’s okay to wait a moment and see if they self-soothe back into deeper sleep.

That said, there are times when it’s best to check in:

• The crying intensifies or continues for more than a minute or two
• Your baby’s movements suggest they’re waking up or uncomfortable
• You notice other signs of distress (like labored breathing or arching)

As you get to know your baby’s unique sounds and patterns, you’ll start to recognize what’s part of normal sleep behavior and what needs your attention. Trust your instincts. A brief pause to observe, followed by a calm, reassuring check-in when needed, can help build confidence for both of you.

Looking for gentle ways to help minimize nighttime disruptions and support more restful sleep for both you and your baby?

Start by establishing a consistent bedtime routine. Simple, calming rituals like a warm bath, bedtime story or dim lighting can help signal that it’s time to wind down. These familiar cues provide comfort and help ease your baby into sleep more smoothly.

Next, make sure your baby’s sleep space is set up for safety and comfort. A firm crib mattress with breathable materials and a snug-fitting sheet creates a supportive foundation for restful sleep. Lullaby Earth mattresses are designed specifically with these needs in mind – they’re breathable, waterproof and made without unnecessary extras, so your baby can sleep safely and soundly (at a price that doesn’t break the bank).

Finally, tune into your baby’s natural sleep cues. Yawning, rubbing eyes, turning their head away or a sudden shift in mood can all be signs that it’s time for rest. Catching these cues early – before your baby becomes overtired – can make bedtime easier and reduce mid-sleep disruptions.

Remember: if your baby cries in their sleep, you’re not alone, and it’s rarely a cause for concern. Most of the time, those brief whimpers or cries are just part of your baby’s natural sleep development. But, if something ever feels off, don’t hesitate to check in or consult your pediatrician – because no one knows your baby better than you do.