The 4-month sleep maturation (regression) can happen between 2-6 months, but most commonly it happens around 4 months because it is triggered by both brain development and developmental milestones.
It gained the term regression because to parents it can seem that their baby’s sleep has regressed. If this is why you landed on this post know you are not alone, I’ve been there myself. But know, that in reality your baby just went through a major developmental milestone. And although it’s difficult to be happy about this while sleep deprived, know that your baby is growing and evolving.
So, what causes the 4-month sleep maturation?
The main reason your baby’s sleep has changed is that your baby's sleep cycles have evolved. Newborn babies have only two sleep cycles, quiet and active sleep (similar to light and deep sleep). However, your baby has now developed additional cycles, which include periods of light sleep, REM and deep sleep. And to make it a just bit more complicated, they also happen at different times of the night.
If you look at the image below you will be able to see how during the first half of the night baby sleeps a deeper and more restorative sleep. Additionally, when they transition between sleep stages they go between deep and light sleep. However, as the night progresses there are no longer stages of deep sleep (especially after roughly 3 am) which is why some babies can wake more frequently after a certain period. So, just know that waking more frequently after you’ve gone to bed is actually biologically normal for your baby since as adults we naturally go to bed after 10 pm.
If you want to understand more about why we sleep, I suggest the book “Why we sleep” by Matthew Walker.
Another factor that can contribute to the 4-month sleep maturation is a developmental milestone. At around 4 months old, babies become more aware of their surroundings and can become easily stimulated by noise or movement, making it harder for them to settle down and fall asleep. So, if you haven’t invested in a good set of blackout blinds, now is your chance. Making the sleep environment darker will eliminate any distractions and help produce melatonin.
So, how can parents cope with the 4-month sleep maturation?
The more turbulent period of this “regression” can only last a few weeks, however, what you may not want to hear, is that this is not a phase or a leap, and therefore will not fully go away. That’s because this is a permanent change in your baby’s sleep cycles. So, if your baby goes into their cot fully asleep, it may take a while before they can sleep through the night on their own.
If you came here looking for help in getting longer stretches of sleep without having to sleep train, I’ve got you covered, you know what’s best for your family. So, make sure you check out my blog post - How to Help Your Baby to Sleep Through the Night by clicking here.
If your goal is to teach independence, and you would like to work with Polly and teach your baby to sleep independently in a gentle and respectful way, click here to see our packages.
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