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How to Get Through the 4-Month Sleep Regression

You probably find yourself in one of two camps right now, and neither is right nor wrong:

Camp A - You’ve been working hard to establish sleep foundations with your little one and suddenly, all your hard work seems to have vanished overnight. Your baby is between 3.5-5 months old, they’ve started rolling, you’ve removed the swaddle, and they’re continuing to wake up every few hours at night even though they used to get some longer stretches in. Heck, they’ve maybe even slept through the night before! Why can’t we go back to that?!


Camp B - Following your baby’s lead, you’ve been going with the flow these first few months. Your baby wakes pretty frequently at night. You feed them. Snuggle them back to sleep. Only for them to wake up another 45 minutes later. It’s exhausting. They’ve been around about 4 months now…shouldn’t they be getting the hang of this sleep thing by now?? You’re exhausted.

So, which one is it??

I’m here to normalize both of these experiences around this time.

There is A LOT going on around 4 months old that will cause a major sleep regression, including the only true physiological development with your child’s sleep - the reorganization of their sleep cycles. That, coupled with rolling and the 4-3 nap transition, make this a rocky time when it comes to sleep.

Sleep Development - The Reorganization of Sleep Around 4 Months Old; aka The 4-Month Sleep Regression

When your baby was born, they only had two stages of sleep that they cycled through - active sleep (REM) and quiet sleep (Non-REM, or NREM). As adults, we actually have four stages of sleep per cycle - REM, NREM Stage 1, Stage 2, and Stage 3).

Around 4 months, usually between 3.5-5 months, your baby will go through a physiological shift from two to four sleep stages. After this cognitive development, your baby now has the exact same organization to their sleep that you do! Unfortunately, this also means that there are more opportunities for wakings as your baby rises and falls between sleep cycles.

If your baby doesn’t yet have the skills to fall asleep (or fall back to sleep) on their own between these sleep cycles, guess what is likely going to happen?? They’re going to signal for you to help them! Whatever was happening as they were initially falling asleep is what they’re looking for now, since they don’t yet know how to do it on their own.

Rolling and Removing the Swaddle

If you haven’t yet, it’s now also time to remove the swaddle, because if your baby hasn’t started rolling yet, it’s coming! And we want to keep them safe.

A rolling baby and a swaddle is not a safe combination.

If your baby is not yet rolling, you can do a slower transition. If they are rolling or showing signs that it could happen, you’ll want to remove the swaddle cold turkey. Read more about removing the swaddle here.

Your child’s pediatrician and these sleep consultants have probably drilled into you that you should always lay your baby down on their back for sleep. Inevitably, your baby is going to roll onto their belly in their crib. And they might be mad about it.

Like, they might be pissed.

What should you do? Should you go back in and turn them? Do you need to start all over?

Here’s my advice: From a developmental perspective, your baby is