What Is the Moro Reflex? (And Why It Wakes Your Baby Up at Night)

You finally get your newborn down, tiptoe out of the room, and then... their arms fly out, their eyes pop open, and the whole peaceful moment is over. If this sounds familiar, meet the Moro reflex — one of the most common (and most disruptive) newborn reflexes out there.

What Is the Moro Reflex?

The Moro reflex is an involuntary startle response every baby is born with. It kicks in when your newborn senses a sudden change in position, a loud noise, or the sensation of falling — their arms and legs fling out, their back arches slightly, and then everything pulls back in, often followed by a cry. It's completely automatic, completely normal, and actually a sign that baby's nervous system is developing exactly as it should.

Why the Moro Reflex Wakes Baby Up at Night

The Moro reflex doesn't clock out at bedtime. It can happen anytime, day or night, and it's especially common during the lighter stages of sleep newborns cycle through often. A shift in position, a settling arm, or even their own sudden movement can be enough to trigger it — and once those arms fly out, baby often startles fully awake (sometimes, right as they were drifting into a deeper stretch of sleep).

Newborns spend a large portion of their sleep in this lighter, active phase, which is exactly why the reflex feels so relentless in those early weeks. It isn't a sign that something's wrong or that baby is uncomfortable. It's simply their nervous system doing what it's designed to do, at a stage in sleep where it's easiest to trigger.

How Long Does the Moro Reflex Last?

The Moro reflex is typically strongest during the first month of life, starts fading around two months, and is usually gone entirely by the 3 to 6 month mark. If it feels intense right now, know that it's a short season, not a forever one.

What Actually Helps

Swaddling is the go-to tool here. Keeping baby's arms snug and close to their body limits how far that startle can travel, which means less of a jolt and a better shot at staying asleep. Just remember: swaddling is only safe once baby is on their back and hasn't started attempting to roll — once that happens, it's time to transition to a sleep sack that leaves arms free.

White noise can help too, by masking the small sounds that might otherwise trigger a startle mid-sleep-cycle. You can shop our favorite white noise machine here. 

Support Through Every Newborn Stage

Reflexes, sleep cycles, startle awakenings — newborn sleep has a lot of moving parts, and it's completely normal to feel like you're troubleshooting something new every week. Our newborn care specialists are trained in safe swaddling, sleep environment setup, and settling techniques that work with baby's natural reflexes instead of against them.

Ready for a full night's sleep, Moro reflex and all? Message our founder, Melissa, and let our team support your family across Dallas/Fort Worth, Houston, Midland/Odessa, and beyond.