Just the mere mention of the 4 month regression can make parents quiver with fear…

As a professional sleep consultant, I hear the term “regression” used in regards to just about every imaginable circumstance. Essentially, if baby doesn’t sleep well for a couple of nights, parents start dropping the ‘R’ word. Some people subscribe to the idea that there’s an eight month regression, a 9 month regression, a 1 year regression, as well as teething regressions, growth spurt regressions, and so on. Others see these as simple hiccups caused by extenuating circumstances.

Ah but the 4 month regression, now that’s the real deal, and it’s permanent.

4 month sleep regression

So in order to understand what’s happening to your baby during this stage, first you need to know a few things about sleep in general. So here’s the science-y part, put simply.

Many of us just think of sleep as an on-or-off situation. You’re either asleep or you’re not. However, sleep actually has a number of different stages that make up the “sleep cycle,” which we go through several times a night.

A sleep cycle looks likes this:

Stage 1 is the initial stage we are all familiar with where you can just feel yourself drifting off, but don’t really feel like you’ve fallen asleep. Anyone who has ever seen their partner nodding off in front of the TV, told them to go to bed, and gotten the canned response of, “I wasn’t sleeping!” knows exactly what this looks like.

Stage 2 is considered the first “true sleep” stage. This is where people tend to realise, once woken up, that they actually were sleeping. For anyone taking a “power nap,” this is as deep as you want to go, or else you’re going to wake up groggy.

Stage 3 is deep and regenerative. Also known as “slow wave” sleep. This is where the body starts repairing and rejuvenating the immune system, muscles tissue, energy stores, and sparks growth and development.

Stage 4 is REM (Rapid Eye Movement) sleep. This is where the brain starts to kick in and consolidates information and memories from the day before. It’s also the stage where we do most of our dreaming.

Once we’ve gone through all of the stages, we either wake up or come close to waking up.

We then start the four stage cycle all over again (until the alarm goes off – or in my case, my 4 year old comes to say good morning).

So what does this have to do with the dreaded 4 month regression we all experience with our babies?

Well, newborn babies only have 2 stages of sleep: Stage 3 and REM. They spend about half their sleep in each stage. Around the third or fourth month, there is a re-organisation of sleep. They embrace the 4-stage cycle of sleep that they’ll continue to follow for the rest of their lives.

When this change takes place, baby moves from 50% REM sleep to 25% in order to make room for those first two stages. So although REM sleep is light, it’s not as light as these 2 new stages that they’re getting used to.

With more time spent in lighter sleep, there’s more of a chance that baby’s going to wake up.

That’s not to say that we want to prevent or avoid baby waking up. Waking up is absolutely natural, and we continue to wake up three, four, five times a night into adulthood and even more in old age.

As adults, however, we’re able to identify certain comforting truths that baby might not be privy to.

When we wake in the night, we’re able to recognise that. “Hey, I’m here in my bed, it’s still night time, it’s 3 hours until up time, and I’m reasonably certain that there are no monsters lurking under my bed. I can go back to sleep” – and we do. Usually so quickly that, the next morning, we don’t even remember the brief encounter with consciousness.

A four month old baby, of course, lacks these critical thinking skills. To a four month old baby who fell asleep at her mother’s breast, the reasoning could go much more to the tune of, “OK, last thing I remember, there was a familiar, beloved face, I was having dinner, and someone was singing me a soothing song about Twinkly Stars. Now I’m alone in this dark room. There’s no food, and there’s probably at least three, possibly four, scary monsters in the immediate vicinity.”

That’s probably an exaggeration, but who knows what goes on in the mind of a four month old baby?

Anyways, now that bub has suddenly realised that Mum’s not around, and they’re not entirely sure where they’ve gone, the natural response is to do a little freaking out.

That stimulates the fight-or-flight response.

Next thing you know, baby’s not going back to sleep without a significant amount of reassurance that everything is OK.

The other major contributor to this 4 month fiasco, I find, is that up until this point, parents have either been putting their baby to sleep with a dummy, or by rocking them, or by breastfeeding them, or some similar technique where baby is helped along on the road to falling asleep.

Now that baby’s spending more time in light sleep, and therefore has a higher probability of waking up, this suddenly becomes a much bigger issue.

These sleep props or sleep associations can be very sneaky indeed.

Although they may be helpful in getting your little one to that initial nodding off stage, the lack of them when they wake up means that baby’s not able to get back to sleep again without some outside help. Cue the fight-or-flight, the crying, and the adrenaline. When this starts happening every half an hour, parents can find themselves in a nightmarish situation.

So, the good news? 

For anyone experiencing the dreaded 4 month regression is that it’s not, in fact, a regression at all. A regression is defined as ‘reversion to an earlier mental or behavioral level’. That’s actually the opposite of what your baby is experiencing. This would be much more aptly titled the “Four Month Progression

So, onto the big question.

What can you do to help your little one adjust?

First off, get all of that light out of baby’s room. I’m not kidding around here. You might think that baby’s room is dark enough, or that baby might not like the dark. That it’s comforting to have a little bit of light coming through the windows or seeping in from the hallway.


Baby’s room should be dark. I mean coal mine on a moonless night kind of dark. Do what you need to do to make this happen!

Newborns and infants are not afraid of the dark.

They are, however, responsive to light. Light tells their brains that it’s time for activity and alertness. The brain secretes hormones accordingly, so we want to keep that nursery absolutely pitch black during naps and bedtime.

The other nemesis of daytime sleep (and night time for that matter, although not nearly as often) is noise.

Whether its the postman ringing the doorbell, the dog warning you that a tractor is in the paddock (something that happens a bit at our place), or something falling on the floor three rooms away; with baby spending more time in lighter sleep, noises will startle them easily. A white noise machine is a great addition to your nursery.

“Wait, isn’t that a prop?” you’re asking. Well, in a way, it is, but it doesn’t require any winding, resetting, reinserting, or parental presence. It’s just there and it can be on as long as baby’s sleeping, so it’s not a prop we need to avoid. It is also really easy to remove when the time is right.

Bedtime routines are also an essential component to getting your baby sleeping well.

Try to keep the routine to about 4 or 5 steps, and don’t end it with a feed. Otherwise, you risk baby nodding off at the breast or the bottle. That will create the dreaded “association” that we talked about earlier.

Keep the feed near the beginning of the routine.

Plan the songs and stories at the end. The whole process should be about 20 – 30 minutes long. Baby should go into their cot while they’re still awake.

If you’re noticing baby getting fussy before bedtime, you’ve probably waited too long. Four month old babies should really only be going about 1.5 to 2.5 hours between snoozes, and bedtime should be between 7pm and 8pm (I’m a big fan of the 7pm end).

Now, there are going to be regressions, actual regressions.

Traveling, illness, cutting teeth, all of these things can cause your little one to have a few bad nights in a row. However, when it comes to the four month “progression,” I’m happy to report that this is a one-time thing.

Once you’re through the 4 month regression period, your baby will have officially moved into the sleep cycle that they’ll essentially be following for the rest of their life. Four glorious stages repeated multiple times a night.

Importantly, by taking this opportunity to teach them the skills they need to string those sleep cycles together, independently, prop-free, without any need for nursing, rocking, or dummies, you’ll have given them a gift that they’ll enjoy for the rest of their young lives.

Of course, some kids are going to take to this process like a fish to water, and some are going to be a little more resistant.

Need some personalised help with your little one?