The Four Month Sleep Regression

March 10, 2021by Katrina Taibinger0

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.

But the four-month regression, everybody agrees on, and for good reason. It’s the real deal, and it’s permanent.

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, told in plain English.

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

Stage 1 is that initial stage we’re 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, which is considered the first “true sleep” stage. This is where people tend to realize, 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, and then start over again until the alarm goes off.

So what does this have to do with the dreaded regression we were talking about originally?

Well, newborn babies only have 2 stages of sleep; stage 3 and REM, and they spend about half their sleep in each stage. But at around the third or fourth month, there is a reorganization of sleep, as they embrace the 4-stage method 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, and 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 recognize that, “Hey, I’m here in my bed, it’s still nighttime, my alarm isn’t going to go off for another three hours, 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 the Teddy Bears’ Picnic. 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 baby’s suddenly realized that Momma’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 and, 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 pacifier, 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, because 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 Four Month Sleep 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,” and that’s actually the opposite of what your baby is experiencing. This would be much more aptly titled the “Four Month Sleep Progression

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

So what does this have to do with the dreaded regression we were talking about originally?

Well, newborn babies only have 2 stages of sleep; stage 3 and REM, and they spend about half their sleep in each stage. But at around the third or fourth month, there is a reorganization of sleep, as they embrace the 4-stage method 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, and 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 recognize that, “Hey, I’m here in my bed, it’s still nighttime, my alarm isn’t going to go off for another three hours, 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 the Teddy Bears’ Picnic. 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 baby’s suddenly realized that Momma’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 and, 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 pacifier, 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, because 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 Four Month Sleep 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,” and that’s actually the opposite of what your baby is experiencing. This would be much more aptly titled the “Four Month Sleep Progression

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by Katrina Taibinger

Trained and certified Pediatric Sleep Consultant and founder of Sleep Through Your Nights

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