Skip the Merlin Sleep Suit: Here’s How to Handle the Swaddle to Sleep Sack Transition

If you’re reading this, you’re probably wondering how to get your baby out of the swaddle without losing every hour of sleep you’ve worked so hard for. 

You’ve seen all the magic products out there, and maybe even considered the Merlin Sleep Suit (no shame, we’ve all Googled it at 2 a.m.)

But here’s the thing: I don’t recommend the Merlin Sleep Suit for this transition. 

Surprising coming from a sleep consultant? I’ll explain exactly why later.

But before we get into how to ditch the swaddle the right way, let’s talk about what’s happening with your baby’s sleep in the first place.

What Does Normal Baby Sleep Look Like?

Between sleep regressions, growth spurts, and the occasional “just because,” baby sleep can feel unpredictable. 

But there are actual reasons behind the regressions that are worth understanding.

• Newborns (0–3 months): Sleep is disorganized. Lots of REM, lots of naps, and a sense of day vs. night is slowly established.

• Around 3–4 months: Sleep architecture shifts. Hello, 4-month sleep regression! Babies start moving through more phases of sleep. REM sleep decreases and your baby no longer falls asleep via REM sleep.

• Around 5 months: K-complexes develop, which promote continuous sleep and memory consolidation. Your baby is ready for a three-nap schedule, naps become predictable and longer, and night feeds can be dropped.

Around four months of age, many parents notice their once-great sleeper start waking up a ton. 

It’s totally normal and biological! But how you support your baby through this transition can make a big difference.

Get free access to my newborn sleep foundations guide to help with the transition.

Hot Take: I Don’t Recommend the Merlin Sleep Suit.

I know so many moms who swear by the Merlin Sleep Suit. It’s marketed as the solution for babies who struggle to sleep once the swaddle is gone.

But here’s why I skip it with my clients every time:

• It restricts movement, which means your baby can’t shift during light sleep to get comfortable, and that’s a skill they need to be able to re-settle throughout the night.

• It limits hip mobility, which isn’t great for development.

• It delays rolling, which is a natural (and helpful) milestone for babies, especially because a lot of babies sleep better on their tummies and sides once they can safely roll.

• It keeps your baby feeling “swaddled” long after it’s time to be free, which often leads to an even harder transition later.

• 45,000 suits sold between September 2025 and February 2026 were recalled because the zipper heads can detach and pose a choking hazard. 

I know it sounds easier to just delay the transition and go with the Merlin Sleep Suit, but in my experience, the longer you wait, the trickier it gets to get them in a sleep suit. 

Which brings me to…

When Should You Ditch the Swaddle?

My general rule is to start transitioning out of the swaddle around 8 weeks, before your baby starts showing signs of rolling.

Why so early? Because your baby still has that newborn-style sleep, making the transition earlier means they’ll adjust before sleep gets more complex. 

You’re also way less likely to deal with a double whammy at 4 months–losing the swaddle and learning a whole new way to sleep at the same time.

How to Make the Transition From Swaddle to Sleep Sack

The transition to a sleep sack doesn’t have to include the Merlin Sleep Suit. Here’s a more gradual approach than cold turkey that works for many of my families:

Start with one arm out.

Do this for the first part of the night and/or naps. Alternate arms during a wake-up or night-to-night so your baby gets used to having both free.

Go both arms out.

Keep the swaddle around their chest if it helps, or move to a sleep sack with both arms fully out.

Once both arms are free, move to the crib so your baby has ample space to stretch, wiggle, and move around.

Check their wake windows. 

Make sure your little one is truly tired enough for sleep. Start with age-appropriate awake windows as a guideline, then adjust based on your baby’s sleepy cues.

Dress for sleep success. 

Once your baby is out of the swaddle, they lose both a layer of warmth and the snugness of the swaddle. Choose sleepwear that compensates for that shift.

Prioritize a solid wind-down routine. 

As babies grow, consistent and predictable pre-sleep routines become even more important. Create a calming routine before naps and bedtime to help their bodies and brains shift into sleep mode smoothly.

Expect a Few Rough Nights…

Yes, it’s a change. And yes, your baby will need time to adjust. But that doesn’t mean it’s the wrong move.

Transitions are just that: transitions. 

Sometimes, transitioning out of the swaddle will seem much more challenging compared to other babies. Some babies are much more reliant on the sensory input of the swaddle and the transition is harder for them. 

It’s normal for your baby to wake more or struggle with sleep after a change. It doesn’t mean something’s broken. It just means they’re figuring it out.

Instead of over-correcting with more night feeds or more rocking, try offering reassurance:

• A hand on their chest

• A gentle back rub

• Replacing the pacifier

Stick with it. Most babies adjust in a few nights, and they’ll come out of it more independent, more mobile, and better equipped to handle lighter sleep cycles.

If you’re worried about sleep training, this blog explores gentle approaches that work for the whole family.

Please Skip the Weighted Sleep Sacks, Too!

Quick note: I don’t recommend weighted sleep products either. The AAP and most pediatric sleep experts advise against them for safety reasons. 

Your baby doesn’t need weight on their chest to sleep well. They need space to move, consistency, and support through the learning curve.

Sleep Will Come

This season will pass, and you’re doing an amazing job, even if it’s 3 a.m. and you’re switching out those arms in the dark.

I know the Merlin Sleep Suit is a tempting option, but I would encourage you not to take the easy choice now to struggle even more later.

If you’re having trouble navigating baby sleep and not sure where to turn, check out my FREE Sleep Studio Resources!

If you want to learn about working together to sleep train your baby, reach out for a consultation.

To better sleep,

Ella