One of the biggest reasons babies sleep with their arms up is the Moro reflex , also known as the startle reflex. This involuntary response happens when babies experience a sudden movement or change in environment, causing them to throw their arms out wide before bringing them back in. It’s an automatic reaction that helps them adjust to sensory changes and self-soothe back to sleep.

A few key things to know about the Moro reflex :

• It’s completely normal and develops in the womb before birth.
• It peaks around 2 months and usually starts to fade by 4 to 6 months .
• Some babies have a more sensitive startle reflex than others, which can influence how often they sleep with their arms up.

Baby sleep patterns are very different from those of adults. Newborns cycle between active sleep (REM) and quiet sleep (deep sleep) much more frequently. This means they are more likely to move, twitch, or even raise their arms while sleeping.

As babies grow, their muscle tone and control improve , and their sleep positions may change. You might notice that around 3 to 6 months, babies start to sleep in different positions as their reflexes settle and they gain better control over their movements.

For parents interested in tracking these evolving sleep patterns, our Sleep Cycle Calculator can help you understand and monitor your baby’s sleep cycles more effectively.

Yes! Sleeping with their arms up is perfectly safe as long as they are placed on their backs to sleep , which is the gold standard for reducing the risk of Sudden Infant Death Syndrome (SIDS) . The American Academy of Pediatrics (AAP) recommends that babies sleep on a firm mattress with a fitted sheet and no loose bedding, pillows, or stuffed animals.

Here’s how to ensure a safe sleep environment :

✔ Always put your baby to sleep on their back (not on their stomach or side).

✔ Use a firm mattress with a snug fitted sheet .

✔ Avoid loose blankets—opt for a sleep sack instead .

✔ Keep the crib free of pillows, bumpers, or plush toys .

Swaddling can help newborns feel secure and reduce the Moro reflex , but not all babies enjoy it. Some prefer the freedom of sleeping with their arms up , especially if they like to self-soothe by touching their face or sucking on their hands.

Swaddling pros :

✅ Helps prevent startle reflex from waking them up.

✅ Provides a cozy, womb-like environment.

Swaddling cons :

🚫 Not all babies like being swaddled.

🚫 Must be stopped once baby starts rolling over (around 3-4 months).

If your baby enjoys sleeping with their arms up, you might want to try a swaddle transition sleep sack , like the Love to Dream™ Swaddle Up , which allows for safe movement while still providing a cozy feeling.

Many parents wonder whether sleeping with arms up is a sign of discomfort, but rest assured—it’s usually just part of your baby’s natural sleep pattern .

Here are a few times to consult a pediatrician :

• If your baby struggles to settle or has difficulty staying asleep for long stretches.
• If they seem extremely stiff or floppy when sleeping.
• If they stop moving one arm or show signs of weakness on one side.

In most cases, though, babies sleep in all sorts of positions , and arms-up sleeping is nothing to worry about!

To help your little one sleep soundly, here are some best practices for good sleep hygiene:

🛏 Create a calming bedtime routine – a warm bath, gentle rocking, or soft music can signal it’s time to sleep.

🌡 Keep the room temperature comfortable – ideally 68-72°F (20-22°C) to prevent overheating.

🌞 Encourage daytime activity – tummy time and gentle play during the day can help babies sleep better at night.

🚼 Practice safe sleep positioning – always put your baby down on their back, on a firm mattress, with no loose bedding .

At the end of the day, babies will sleep however they feel most comfortable. If your little one prefers to sleep with their arms up, rest easy—it’s just their natural way of settling into dreamland! And hey, if they look adorable doing it, that’s just a bonus. 😊