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The Fourth Month Sleep Regression

Updated: Jan 30, 2022

As a professional sleep consultant, I hear the word ‘regression’ used in relation to just about every imaginable circumstance. If babies don’t sleep well for a couple of nights parents start throwing around the ‘R’ word. People subscribe to the idea that there’s an eight-month, nine-month, a 1-year regression, as well as teething, growth spurt regressions and so on. Others just see these are simple hiccups caused by extenuating circumstances.

However, the fourth month sleep regression everybody agrees on, and for good reason. It’s the real deal and it’s permanent.

To fully understand what’s happening to your baby around the four-month mark, first you need to know a few things about sleep in general. So, here’s the ‘science of sleep’ told in plain English.

Many of us think that sleep is either 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.

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

Stage 2 is also ‘light’ sleep but is considered the first “true sleep” stage. You are still in light sleep, but this is when people tend to realise, once woken up, that they were sleeping. If you ever want to take a power nap, this is as far as you should go or else you’ll wake up feeling groggy.

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

Stage 4 is known as REM (Rapid Eye Movement) sleep. During REM sleep your brain starts working hard and consolidates information and memories from the day before. This is the stage where we do most of our dreaming.

Once we’ve gone through all of these stages, we either wake up or come close to, and then start over again until the alarm goes off.

So, you ask what does this have to do with the dreaded four-month regression we were originally talking about?

Well, a newborn baby only has two stages of sleep: Stage 3 and REM. They spend about half of their cycle in each stage. But, around the 3-4 month mark of life there is a reorganization of sleep where a baby embraces on the 4-stage method of sleep where their sleep with stay for the rest of their life.

As this change takes place baby moves from 50% REM sleep to 25% to make room for the first two stages. Although REM is also a stage of ‘light’ sleep, it’s not as light as the first two stages that baby is getting use to. With more time spent in lighter sleep, there’s more of a chance baby is going to wake up.

We don’t want to prevent or avoid baby waking up as this is absolutely natural. We continue to wake up 3 -5 times a night into adulthood and even more in older age.

However, when we wake as adults, we are able to identify certain comforting truths that baby may not be privy too. We’re able to recognise that, “Hey, I’m here in my bed, it’s still nighttime, my alarm isn’t going off for another three hours and I’m pretty sure there’s no monsters hanging out 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.

Obviously, a four-month-old baby lacks these critical thinking skills. A four-month-old baby who fell asleep at her mother’s breast could go much more to the tune of “OK, the last thing I remember was a familiar loving face, I was having dinner and someone was singing a soothing song about stars in the sky. Now I’m alone in this dark room, there’s no food or singing and there’s probably at least three, maybe four, scary monsters under my bed.”

Okay, that’s probably an exaggeration, but who knows what’s going through the mind of a four-month-old baby?

Anyway, now that bub realises Mumma’s not around and they’re not quite sure where she's gone, it’s natural that baby’s going to do a little freaking out. That stimulates the fight or flight response and before you know it baby’s not going back to sleep without a significant amount of reassurance that everything is OK.

The other major contributor to this four-month debacle, I find, is that up until this point, parents have been helping their baby to sleep. Whether that involves giving baby a pacifier, breastfeeding them, rocking them, or by some similar technique where baby is assisted along the path to falling asleep.

This, together with the fact that baby’s now spending more time in light sleep and has a higher probability of waking up, causes a bigger issue. These sleep props or associations can be very sneaky. Although they can be helpful in getting your little one to the initial nodding off stage, their absence when they wake up means baby is not able to get back to sleep without some outside help. Cue the fight-or-flight, the crying, and the adrenaline. When this starts occurring every half an hour parents can find themselves in a nightmare situation.

So, if you think about it, the dreaded Four Month Sleep Regression is 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 you baby is experiencing. “Four Month Progression” would be a more suitable title for this development stage.

So, the big question – what can you do to help your little one adjust?

Firstly, make your baby’s room as dark as possible. I’m not kidding around here. You may think that your baby’s room is dark enough or that baby may not like the dark and is comforted by a little light seeping in from the windows or hallway.


Baby’s room should be dark, and I mean coal mine on a moonless night dark. Do anything you can to get the room pitch black. Hang garbage bags over the windows or cover them with tinfoil if you must. (Just be prepared to explain it to the cops when the neighbors dob you in for growing a crop!)

Newborns and infants are not scared of the dark, but they are however responsive to light. Light signals to their brains that it’s time for activity and alertness and their brains then secrete hormones accordingly. We want to keep that nursery absolutely pitch-black during naps and bedtime.

The other archenemy of daytime sleep (and nighttime for that matter but not nearly as often) is noise. Whether it’s the delivery man ringing the doorbell, the dog warning you you’re under attack by the possums in the backyard, or something falling on the floor three rooms away. With baby spending more time in lighter sleep, noises will startle them and easily wake them up. I highly recommend using a white noise machine in your nursery.

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

A bedtime routine is a vital 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 bottle and that will create the dreaded “association” that we talked about earlier.

Therefore, try keeping the feed near the beginning of the routine and plan the songs, stories and getting into PJs towards the end. The bedtime process should be about 20-30 minutes long and baby should go into their bassinet/cot awake.

If you’re noticing bub is getting fussy before bedtime, you’ve probably waited too long. Four-month-old babies should really have about two hours awake time between snoozes with bedtime around 7 and 8pm, depending how day naps go.

Now, there are going to be other actual regressions you face as your little one grows. Illness, travelling, cutting teeth, all 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 pleased to report that this is a one-time thing. Once you get through all this, your baby will have officially moved into the sleep cycle they’ll be following for the rest of their life. Four wonderful stages repeated multiple time a night.

By taking this opportunity to teach them the skills they need to string those cycles together independently, prop-free, without any rocking, nursing, or pacifiers, gives 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. Others are going to be a little more resistant. If yours falls into the former category, count yourself as lucky, take delight in your success and go ahead and gloat about it on Facebook.

For those of you in the latter situation, I’m happy to help in any way I can. Just visit my website or give me a call and we can work on a more customised program for your little one. The most common thing I hear from parents who have worked with sleep consultants is, “I can’t believe I waited so long to get some help!”

So, if you’re considering hiring a consultant, now is the perfect time. I offer a free 15-minute free initial consultation so I can get to know the specifics about your little one’s situation. Book a call now and we can move forward as soon as you’re ready to get your little one going down well and sleeping through the night!

Contact our sleep consultant today to book your free introductory consultation.


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