The 4 Month Sleep Regression Mystery Explained

 In Baby Sleep Tips

The 4 month sleep regression that some babies go through can seem so mysterious.

Why does a baby who sleeps perfectly at 3.5 months produce one nightmarish night after another just two weeks later? And more importantly, why do some babies seem to escape unscathed?

To understand the frustration and confusion that often accompany this regression, let’s consider a hypothetical friendship between Mum A (we’ll call her Abby) and Mum B (We’ll call her Barb).

baby girl sleeping on bed wearing pink clothing.

A Sleep Regression Case Study

Abby and Barb are neighbours and friends. They were excited to learn that they were both due to give birth in the same month. Both women excitedly prepared for the arrival of their little ones, and sympathised with each other during the sleepless first weeks after birth.

They celebrated together when their babes started sleeping longer stretches at night. And before long, both little ones were only waking for 2 meals each night.

They both breastfed exclusively and put their babies in their bassinets for sleep. Their parenting choices seemed so similar that they joked they could switch the babies for a day and the little ones wouldn’t notice.

They both felt so relieved that they had been blessed with “good sleepers”. But then, at almost exactly 4 months, the dreaded curse took a victim.

Abby’s babe continued to sleep like a dream, but Barb’s little one began to struggle immensely.

In just a matter of days, the sleep schedule at Barb’s house had deteriorated to 4-6 feeds every night. Her baby’s naps were barely longer than 30 minutes. Barb couldn’t decide if she was more frustrated by the lack of sleep, or the inexplicable change in her baby.

If you’ve ever experienced this regression with one of your own, I’m sure you have no trouble sympathising with Barb.

In my work as an infant and toddler sleep coach, I always begin by asking my clients when the sleep problems began.

It’s rather alarming how many 3 and 4 year olds of my clients started having sleep issues at the 4 month mark! For some babies the 4 month regression really is the beginning of the end (as far as decent sleep goes).

[click_to_tweet tweet=”It’s rather alarming how many 3 and 4 year olds of my clients started having sleep issues at the 4 month mark! #sleepregression #babysleep @sleepymumsvillage” quote=”It’s rather alarming how many 3 and 4 year olds of my clients started having sleep issues at the 4 month mark!” theme=””]

Sadly, when severe sleep issues arise during the 4 month regression, they often linger for years. Take hope though, because (as mysterious as it seems) the issues that some babies face during this infamous regression are completely preventable.

Why Does One Baby Go Through a Sleep Regression and not the Other?

Let’s look at Abby and Barb’s story again, but through the babies’ perspectives.

These little ones are born with only two sleep stages:

  • the Deep Sleep Stage
  • and the REM Sleep

This means that when they are asleep, they’re either dreaming (REM Sleep), or sleeping so deeply (Deep Sleep) that they typically only wake when hungry or wet.

This is why it is often possible for a 2 month old baby to sleep in a bright room full of busy people. This is also why both babies seemed to settle so easily into a schedule of 2 feeds per night.

Once they began to take the majority of their calories during the day, they simply started waking less in the night. However, the number of night feedings alone is really no indicator of how healthy the child’s relationship is with sleep.

For example, Abby gave her baby opportunities to try to sleep on her own in a quiet and dark place from the start. She never left her to cry and always helped her get to sleep if she couldn’t do it herself. However, she did give her baby independent sleep opportunities and sometimes it worked!

In the night, she’d wait until her babe was fully awake before she fed her. She also put her down awake after the feeding. This little one had the foundation of a healthy understanding of sleep and her role in it.

In contrast, Barb had always fed her little one to sleep. She went directly to her in the night and fed her right away. During these night feeds, she would often change the nappy, and nurse the baby for another 10 minutes to get her baby back to sleep.

Although this little one was sleeping decent stretches at night, her relationship with sleep was almost non-existent. All she really knew was breastfeeding. She didn’t understand that sleep exists as a separate entity. The answer to any uncomfortable feeling that she had (including fatigue) was the breast.

Now, they entered the 4 month sleep regression.

[click_to_tweet tweet=”Why does one baby go through a sleep regression and not the other? #sleepregression #babysleep @sleepymumsvillage” quote=”Why does one baby go through a sleep regression and not the other?” theme=””]

What Exactly Is the 4 Month Sleep Regression?

This “regression” is really more of a developmental “progression”. It is the development of the lighter stages of sleep that we’re familiar with as adults.

This means that a baby will now be waking 3 to 4 times as often throughout the night. Now the true colours of their relationship with sleep will be revealed.

In Abby’s case, her daughter woke several times in the night when she was startled by sounds, or even her own body movements. These things wouldn’t have disturbed her in her normal “deep sleep” stage, but the development of her lighter sleep stages left her much more sensitive to her surroundings.

Fortunately, she was comfortable enough with her sleep independence and put herself right back to sleep. Her mother didn’t even hear her in the night.

When the same changes began to happen with Barb’s baby, she cried angrily for the breast every time. Within a few weeks, this baby would start to consume quite a bit more calories in the night. All because of how much she had to eat just to get back to sleep.

In fact, her body may even develop a habit of waking 4 to 6 times in the night to eat since that’s what happens every night. She struggles to make it past a single sleep cycle during the day and her nap schedule is a wreck!

The difference in the two babies is more apparent than ever.

What Can I Do During the 4 Month Sleep Regression?

Don’t become overly confident in your child’s sleeping abilities just because they sleep for long stretches at night as a newborn.

If your baby has not yet reached 4 months, then start now to help him or her develop some independent sleep skills. Find resources that educate you about independent infant sleep, and what you can reasonably expect from your child in each of those first months.

If you’ve already seen the ugly side of the 4 month sleep regression, then make a commitment to get some help for you and your child. Don’t wait for them to “grow out of it”.

If they’ve responded negatively during this 4 month sleep regression, then you have a clear sign that your child’s relationship with sleep needs some support.

Find a sleep program, book, or sleep coach that can help you to introduce independent sleep skills as soon as possible!

Sleep well!

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Showing 2 comments
  • Amanda

    My oldest had this problem started at 4 months after getting very ill. Sadly it continued until he was in first or second grade.

    • Ann

      Oh no, that’s a long time to be with sleep issues. Hopefully, it’s all settled down now.

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