What Is Moro Reflex in Newborns? And Why Is It Waking Up My Baby?

"Hi, I’m Debra – a Certified Sleep Sense Consultant based here in sunny Singapore. I work closely with exhausted mums and dads who are navigating the unpredictable world of newborn sleep. 

Let’s talk about a term many parents have heard but few fully understand: the Moro reflex, or what’s commonly known as the startle reflex. 

Picture this: you’ve just spent 45 minutes gently rocking your newborn to sleep. You place them ever-so-carefully in the crib, praying they stay asleep. Then suddenly—flailing arms, a startled gasp—and just like that, your little one is wide awake again. 

Frustrating? Absolutely. But this response is natural. It’s called the Moro reflex, and every baby is born with it. 

What Exactly Is the Moro Reflex? 

The Moro reflex is an involuntary response present from birth. When your baby is startled by a loud sound, a sudden movement, or even a shift in head position, they react by: 

• Throwing their arms and legs outward 

• Opening their fingers 

• Arching their back 

• Letting out a cry 

• Then drawing the limbs back toward their body 

This reflex is part of your baby’s primitive survival instincts and typically fades around 4 to 6 months of age. 

How the Moro Reflex Affects Baby Sleep 

The Moro reflex may serve a biological purpose, but let’s be real—it’s a major sleep disruptor. 

Many parents I work with in Singapore tell me that just when their baby enters deeper sleep, the Moro reflex kicks in and abruptly wakes them. This repeated disruption leads to:

• Short naps (those 20–30 minute catnaps that leave baby cranky) 

• Frequent night wakings 

• Increased reliance on rocking or nursing to fall asleep again 

This is where sleep training a baby comes into play. Teaching your child how to self-soothe can make a massive difference—especially when Moro reflexes are wreaking havoc. 

7 Ways to Help Your Baby Cope With Moro Reflex 

Here are my go-to methods for minimizing the impact of Moro reflex, all rooted in sleep training a baby and improving rest: 

1. Swaddle Smartly 

Swaddling creates a womb-like cocoon that restricts sudden movements and dampens the startle. Choose lightweight cotton muslin for Singapore’s climate. 

2. White Noise Works 

Loud shushing or white noise can mask sudden sounds that trigger the reflex, especially during light sleep cycles. 

3. Practice Gentle Transfers 

Hold your baby close to your chest and lower them slowly into the crib, keeping your hands on them a few seconds longer after the drop. This reduces startle triggers. 

4. Create a Consistent Bedtime Routine 

Repetition builds security. Incorporate gentle rocking, lullabies, and dim lights to transition to sleep. 

5. Use a Sleep Sack When Baby Outgrows the Swaddle 

Sleep sacks offer mild restrictions while giving babies the freedom to move safely once they’re rolling. 

6. Optimize the Sleep Environment 

Keep the room cool, dark, and distraction-free. Blackout curtains and a consistent sleep space are crucial when sleep training a baby. 

7. Begin Gentle Sleep Training 

Once your baby is developmentally ready (usually around 4 months), structured sleep training helps them self-soothe and settle even when the Moro reflex kicks in. 

When Should You Worry About Moro Reflex? 

Most babies outgrow this reflex by 6 months. However, if your child still has a strong startle reflex beyond that, or if they aren’t showing it at all in infancy, it’s a good idea to consult your pediatrician. 

How Sleep Training a Baby Helps With Moro Reflex 

Here in Singapore, I’ve supported many families in managing the transition from reflex-driven sleep to self-soothing sleep. Sleep training a baby builds your child’s confidence to fall back asleep independently—even if the Moro reflex startles them awake. 

With the right tools, guidance, and sleep routines, Moro reflex doesn’t have to rob you of your nights of peace. 

Let’s Build Healthy Sleep Habits—Together 

You’re not alone. As a certified Sleep Sense consultant, I help families across Singapore get their sleep back—guilt-free, tear-free, and science-based. 

If you’re struggling with Moro reflex, short naps, or multiple night wakings, you don’t have to figure it out alone. 

👉 Explore our Services Page to learn more about how I can support you and your baby toward better sleep. 

FAQs 

Why do babies wake up because of the Moro reflex? 

Babies wake up due to the Moro reflex because sudden sensations—like being laid down or noise—trigger an involuntary startle response that disrupts their sleep. 

How do I stop my baby from waking up with startle reflexes? 

When should I worry about Moro reflex? 

How to stop babies' arms from waking them up? 

Why does my baby wake himself up in active sleep?