What Is The Four Month Sleep Regression

I remember sitting in the rocking chair in my son’s room in the wee hours of the morning, my little guy sleeping soundly on my chest. He was a little over 4 months old at that time.

We had got through our first plane trip home to visit the grandparents. Then the cold that followed and the arrival of first two teeth. We got the reflux under control, and yet my son STILL wasn’t sleeping well.

He’d take hours to fall asleep and was up so frequently in the night I had given up sleeping in my own bed. I began the habit of nursing him to sleep then falling asleep myself in that rocking chair for fear of moving him. I was exhausted, sore, and starting to lose my grip.

On that particular night I was scrolling on my phone as the white noise blasted out of the speaker, trying to figure out WHY my child still wasn’t sleeping. So I googled “Why isn’t my 4 month old sleeping”

The answer that popped up? Four Month Sleep Regression.

So many search hits came up with this answer. Was it real? Was it a myth? Why did it happen? I realized that with the absence of anything else like a cold or teeth to affect my son’s sleep, we must be in the middle of Four Month Sleep Regression.


To get it out of the way, Four month sleep regression is not a myth.


Some babies make it through this phase with barely a blip in their sleep habits. Other babies hit it like a freight train.

Regression usually shows up as babies who were sleeping well and suddenly start waking frequently and fuss more and cut naps, or babies who were sleeping poorly and it suddenly gets worse. It’s an exhausting time for parents that seems like it will go on without end, but will usually last anywhere between 1-4 weeks.


So what is Four Month Sleep Regression and WHY oh WHY does it happen?

There is a lack of solid scientific research and studies on sleep regression because each baby is so unique it’s hard to get a good study sample. But here is what we do know about Sleep Regressions and why it happens.


Your baby is Growing

Between 3-5 months of age, baby starts hitting some major physical and developmental milestones. Rolling over, smiling, laughing, babbling, and the starting of sitting, are all huge and important skills that take up a lot of baby’s developing brain. A baby learning new skills will sometimes want to practice them at night, and this practice and development can disturb sleep.


Your baby’s sleep is Changing

Also, this is the point where baby’s sleep cycles start changing. REM sleep is very important and very restorative. At around 4 months of age baby’s sleep cycles start changing to more adult-type cycles as they cycle through REM and non-REM sleep. These changes can create brief awake periods between sleep cycles which can cause more frequent night wakings.


Your baby is Learning

There is also a school of thought that around 4 months of age is when baby becomes more ‘aware’ of the props and supports that they require to fall asleep. Rocking your baby to sleep at bedtime means they will learn that every time they wake they need to be rocked to sleep again. Four months can be a difficult time because babies become aware of those props that were already in existence. Or, in a parent’s desperation for sleep, they introduce new props like a soother or nursing to sleep. The baby will now rely on these to connect the sleep cycles after awakening at night.

So what can you about the Four Month Sleep Regression?

Start getting your baby on the right track for sleep and create good sleep habits. This can start from the day you bring your baby home and good sleep hygiene can last a life time. If you already have a good sleeper, keep up the routine through the regression. Introducing new props, such as co-sleeping, rocking, or nursing to sleep can create a sleep-association that your baby will continue needing to fall asleep after the regression is over.

Keep your baby’s tank full. Using the MAMA Method helps making sure baby is getting all the calories they need during the day and night.

And know that it will pass (even though it doesn’t feel like it) and you are a GOOD MAMA (even though you may not think it). You know your baby best and you’re doing an awesome job.


If you need help with sleep, contact me for a consultation.

Because I hate to tell you, there can also be a regression at 8 months…and a year…and 18 months.


Share this post

Are you looking for support in your parenting journey? Click here to chat with a registered nurse.