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Written by Lavinia
Certified Paediatric Sleep Consultant
16 October 2020

The 4 month Sleep Regression

If you were to google the term "sleep regression", it might appear like there is a sleep regression pretty much every month of baby's first year. I do not agree that that is in fact true.

The only true sleep "regression" in my opinion is the infamous 4 month one, as it is the only one with scientific basis. There is a change in sleep organisation in a baby at 3-4 months of age, which has the  effect of manifesting as a sleep regression in primarily the sleep-prop dependent babies ie babies reliant on external factors for sleep (eg being rocked, patted, fed to sleep or with a pacifier). For the babies who were not sleep prop dependent, prior to this sleep re-organisation, tend to sail through this period without parents noticing any change in their sleep at all.

Here's Why.

Let's first understand a little bit about the science behind sleep.  Many of us generally consider sleeping to be either a necessity or a luxury. It's either true that you're asleep or false. Yet, sleep consists of a series of stages that make up a sleep cycle. We move in and out sleep cycles through the night. 

We're all familiar with the first stage of sleep, when you start yourself drifting off but don't feel like you have completely fallen asleep.  Eg when you see your partner nodding off in front of the screen, but when you point it out to him, you get the the standard "I wasn't sleeping!" response.

The second stage of sleep is the first stage of "true" sleep. If you are woken up from this sleep, you would realise that you were actually sleeping. This is as deep a sleep as you would like to go to get a "power" nap, as if you went any deeper and was then woken up you are likely to feel groggy.

The third stage of sleep is a deep and regenerative and is  known as "slow wave" sleep. The body's immune system, muscle tissue, energy stores begin to repair and rejuvenate. This stage of sleep also promotes growth and development in babies.

The fourth stage of sleep is REM (rapid eye movement) sleep. Around this time, your brain begins to activate, helping you consolidate, remember and understand what happened the day before. We do most of our dreaming during this stage of sleep.

After going through each phase, we eventually awaken or are on the verge of waking up, only to fall back asleep till the alarm goes off.

Now how does this relate to 4 month old babies?

Well, newborn babies only go through two stages of sleep, and each stage accounts for around half of their total sleep time. By the third or fourth month, however, their sleep is re-organised into the 4-stage system of sleep that they will follow for the rest of their life.

As a result of this, REM sleep drops from 50% to 25%, making way for the earlier stages. The baby now has two new stages of sleep, both of which are lighter than REM sleep, increasing the likelihood that the infant will wake.

It doesn't mean we want to keep the infant from waking up. It is completely normal to awaken several times throughout the night, and this pattern persists well into maturity and even into old life. As mentioned above, we all have sleep cycles we go in and out of through the night.

But, as adults, most of us realise, upon waking in the middle of the night, that "Hey, I'm here in my bed, it's still nighttime, and I can go back to sleep."  Often times, everything happens so swiftly that by the next morning, we have forgotten ever waking up at all.

These are critical thinking skills that a four-month-old simply doesn't have yet. A four-month-old who has fallen asleep while nursing or being rocked to sleep is likely to "freak out" to some extent upon realising that he is no longer in his mother or father's arms. Because of the activation of the "fight or flight" mechanism, the infant will not go back to sleep unless they are given extensive reassurance that everything is fine.

One of the main reasons why babies haven't learned to fall asleep on their own by four months is if their parents have been using a pacifier, carrying, patting or rocking them to sleep, feeding or doing or some other method to help them go off to sleep.

This has become a much more pressing concern now that the infant is spending more time in light sleep and is more likely to wake up. These sleep props, also known as sleep associations, may assist your baby fall asleep initially, but after they awaken, they prevent baby from falling back to sleep on his or her own. Start the adrenaline pumping, the sobbing, and the "fight or flight" response. This can become a nightmare for parents when it occurs every hour.

Now for for the babies who were independent sleepers BEFORE this sleep re-organisation took place - they tend to sail though this without the parents noticing any change in their sleep. Because even if they wake from the lighter new stages of sleep, they go right back to sleep on their own, often without their parents knowing that they woke at all.

So, to summarise, the 4 month sleep "regression" is in fact based on on progression or maturation in your baby's sleep. Scientifically, it is more appropriately termed a sleep progression than a sleep regression. And it results in a more crying in the night by babies who were sleep prop dependent at the time it happened.

The truth is that, like it or not, the 4 stage sleep cycle is here to stay. So if you would like your baby to be sleeping well on his own through the night, then the no. 1 way toward achieving this is to allow her to learn how to sleep without being reliant on sleep props.  To create a more tailored plan for your child, simply contact me through my website or give me a call. One of the most often comments I receive from people I've helped is, "I can't believe I waited so long to get some help!" This is the perfect opportunity to bring in an expert to give the right guidance. 

Article written by Lavinia
Certified Paediatric Sleep Consultant
Based in Singapore
Trained in the Sleep Sense Program

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