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4 Month Sleep Regression

Updated: 5 days ago

Have you heard whispers of the 4 month sleep regression? Most new parents are unaware of the looming changes coming to their baby’s sleep and can often start to worry when they’re told the troubled stories about this regression.

A baby in the 4 month sleep regression having disrupted sleep
4 month sleep regression is really a progression

To avoid concern about this regression, it’s important to understand what it actually is. When we understand what we’re dealing with, it can be easier to accept and manage. But before we jump into the depths of understanding what the 4 month regression is, let’s take a step back and further explore newborn sleep presentations.


Firstly, you should know that it is really normal for babies to sleep extremely well in the first 3-4 month of life. This period of time is commonly know as the ‘missing 4th trimester’. As newborn babies are still so new to the world, they are neurologically immature, and are cute, little lumps that need to feed, sleep and poop. In typical newborn presentation, this is pretty much all they do and this missing 4th trimester is an easy-breezy period of time for many new parents. Additionally, the newborn body clock is not yet even developed, they are still relying on their stores of melatonin, and they don’t even have sleep cycles.

During this period, newborn babies will usually only wake for a need, such as hunger or a nappy change. After a brief wake window, once their needs have been met, they will usually settle back to sleep. This is quite a typical sleep presentation for a newborn baby. So whilst you may feel like your baby is the perfect little sleep angel, and all your hard work around establishing sleep is totally paying off, don’t be food too easily. You’re not out of the troubled sleep zone yet ;)

Overall, sleep in the first 4 months is actually quite simple. There are no sleep cycles or obvious sleep patterns. They have sleep stages; active sleep and quiet sleep. Active sleep is an immature REM sleep, where your baby may move, open their eyes, groan, cry out or breathe noisily or irregularly. When your baby is in quiet sleep, they will be still, During quiet sleep, they will lie relatively still, have floppy limbs and will breathe more evenly. Babies cycle sporadically through these phases with no real pattern but overall, they will spend 50% of their time in active sleep and 50% of their time in quiet sleep. Each stage is random in length and can happen at any point during their sleep phase.


And this is the way their sleep will present until the 4 month sleep regression, otherwise known as the 4 month sleep PROgression. Each regression and leap your child goes through is actually a sign that they are developing, as each disruption to their sleep through the regression is related to a developmental leap.


What development is the dreaded 4 month sleep regression related to, I hear you ask? Well, it’s due to the development of the night sleep cycles. A baby’s sleep moves from sporadic, active/quiet sleep, to a structured adult-like sleep pattern where we see consistent cycles.


the stages of a sleep cycle
The typical pattern of a sleep cycle

As per the image here, you can see the process of a sleep cycle that commences through the regression. As a baby falls asleep, they transition from light sleep to deep sleep and back into their light sleep again. At this point, they will subconsciously check their surroundings to ensure all is safe and the same as when they fell asleep, and transition into their next light sleep phase, linking their sleep cycles.

This regression will typically occur somewhere between 4-6 months of age, but we can start to see some minor disrupted sleep from around the 3 month mark. Through this regression, many babies will wake as they come to the end of their sleep cycle, but not all will transition into their next cycle independently. If a baby does wake at the end of their cycle, they will commonly seek the same level of assistance that is offered whenever they are settled or resettled, or they will seek a physical need to be met, such as a feed or nappy change, or just comfort in general.

It is at these wakings when the regression can cause a big and challenging impact, as parents are used to long blocks of sleep, to waking 2-4 hourly and needing to provide their baby assistance.

It can be hard to be sure whether your baby is in the thick of a regression, but there are some notable signs which can help you decide if the 4 month sleep regression has reared its ugly head.

Signs that your baby is in the 4 month regression:

  • Increased fussiness

  • Multiple night wakings

  • Reduced naps or “disaster naps”

  • Changes in appetite

  • Difficulty falling asleep

  • Notably reduced total sleep time

  • Waking 2-4 hourly at night

This regression can present almost overnight and unfortunately, it can’t be completely avoided. However, there is a significant difference in impact for a baby who has healthy sleep habits and independent sleep skills vs a baby who doesn’t. This means that you can prepare you and your baby for the regression to reduce the impact.

To navigate the preparation, there are two components which are most important:

  • Sufficient day sleep, in quantity and balance

  • Self-Settling and Resettling skills


You can view my blog on day sleep requirements here: Sleep Needs


If you can ensure that your baby has adequate day sleep in quantity, but also ensure their sleep/wake drive is balanced properly, then you avoid over tiredness. When a baby is over tired, they have a rise of cortisol, and this triggers adrenalin to be released into their system. An over tired baby, who is full of adrenalin, is too wired to fall asleep and stay asleep, hence increasing the negative impacts of the regression. A baby who is well rested and has enough sleep for their age is more able to stay asleep and resettle easier.


A baby sleeping during the 4 month sleep regression
The 4 month sleep regression lasts 2-6 weeks

As for self-settling and resettling skills - this can sound overwhelming because most parents think that encouraging self-settling and resettling skills means to apply a cry-based level of sleep training. But, we can encourage independent sleep skills by using a gentle, responsive, in-the-room method that is supportive to both you and your baby. We can certainly establish healthy sleep habits and navigate the regression with a responsive and respectful approach.


But do keep in mind that self-settling and resettling skills are not the holy-grail when it comes to sleep improvements. You can read more about this here on my blog: Self-Settling vs Resettling vs- Self-Soothing


If you can encourage some level of self-settling and resettling skills, all whilst avoiding over tiredness, you will ease the impact of the 4 month sleep regression.


Now that you have a strategy to prepare for the regression, there are some steps you can follow when the regression commences:


  • Maintain your child's current nap schedule - you can grab a copy of my free Day Sleep Guide here

  • Continue to aim for their recommended sleep quantity in the 24 hour period

  • Put your child to bed confidently

  • Spend lots of quality time during the day with your child to ease the separation anxiety

  • Provide your child with lots of opportunities to practice their new skills during awake times

  • Foster their independent play during the day

  • Establish a good wind-down routine, with lots of quality quiet time as part of the wind-down

Whilst the regression can be disruptive, it shouldn’t be so significantly difficult that you’re left wondering how everyone else is able to navigate this regression, but you can’t. It should cause ripples, but nothing too significant. If your baby’s sleep falls apart drastically, leaving your chronically sleep deprived or exhausted, then there is more going on than just a regression.


If you follow the recommended steps to navigate the regression, then you should see that effects of the regression subside within 2-6 weeks, and your baby will re-establish their good sleep habits. If your baby’s sleep presentation is disrupted for more than 6 weeks, or the regression period is exacerbated, then we need to consider exploring other causes of your child’s sleep presentation.


This is where we start to explore the difference between biologically normal sleep and sleep which falls beyond the realm of normal. If you are in this space, and would like to know more, your next step is to read my blogs:


If you’re struggling with the regression, or any component of your child’s sleep and need some 1:1 help to navigate your concerns, book in for a 15 minute free Discovery Call:



Forever bringing sleep to families,


shereen nielsen sleep consultant






I'm Shereen Nielsen, a certified Sleep Consultant specialising in infants and children from birth to 15 years old. With over seven years of experience, I've assisted over 4000 families in achieving better sleep. Additionally, I serve as a lecturer and mentor, guiding aspiring sleep consultants on their path to certification through my internationally recognised online Sleep Consultant Course.


Phone: +61419820474


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