The 4-month Sleep Regression

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When your little one goes through the four-month sleep regression, you will know it! Like all regressions, this is actually a developmental “progression”. Your baby is undergoing tremendous brain development (also referred to as developmental leaps). Wonder Week 12, “The World of Smooth Transitions” is the leap your infant is going through during this sleep regression.

Newborn Sleep

For the first 6-8 weeks of life, your infant has “immature” sleep cycles. What does this mean? It means that their circadian rhythm is still sorting itself out. Your little one is working through day/night confusion and sleep is disorganized. You may notice that your baby will have a 3 hour nap followed by a 10 minute nap. Sleep is inconsistent to say the least as sleep cycles are all over the place. Newborns also experience deep stages of sleep. You may notice that you newborn sleeps anywhere. . . even in noisy and bright environments. As your infant approaches the 8 week mark, sleep environment is even more crucial. Read more about sleep environment here. Another way to maximize sleep during the first several months is to use a swaddle. Read more about swaddles here

There is SO much to know about Newborn sleep. I have written over 30 pages of information in my Newborn Sleep Guide.

Why does my baby wake up after 30-45 minutes?

As mentioned above, your 4 month old (ish) is undergoing brain development. Part of this development includes permanent changes to their sleep cycle. Their circadian rhythm is establishing itself, sleep cycles are maturing and becoming more organized. Your infant is also experiencing lighter stages of sleep. Rather than transitioning between 2 stages of sleep, your baby is now experiencing 4 stages of sleep. Sleep cycles are also matured in the sense that they are similar to an adult’s sleep cycles. . . the only difference is that baby’s sleep cycles are shorter than ours. Adult sleep cycles are 60-90 minutes and babies’ sleep cycles are 30-45 minutes. Do you notice that your little one will wake after a short 30-45 minute nap? This is why! They are waking up after a sleep cycle and looking for their sleep crutch. A sleep crutch is anything that you use to put your baby to sleep. Most often this is a bottle/nursing, rocking or holding. Prior to this regression you were able to “get by” by relying on these sleep crutches. You were able to rock your baby to sleep, put them in their crib and walk away and it is like a truck hits you when the 4 month regression strikes because SURPRISE! That baby wakes up the moment you attempt to lay them down. As newborns, they immediately fell into deep stages of sleep and were easily transferred. Now, they are in lighter stages of sleep and notice if you try to lay them down and walk away.

Stages of Sleep

There are 4 stages of sleep. Stage 1 is a very light stage of sleep which is described as “Falling asleep” or “dozing off”. Stage 2 is still a light stage of sleep where your body temperature starts to lower and prepare for deeper stages of sleep. Stage 3 is deep and restorative. In this stage, body tissues repair, the body’s immune system and energy levels are recharged. Stage 4 is where we dream. This stage is also referred to as REM sleep. This is where memories and sensory information is processed. Newborns spent more of their time in stage 3 and 4 of sleep. Once the “regression” hits, they spend time in all 4 stages of sleep. These lighter stages of sleep are where they are more easily awoken and babies rely on their sleep crutch to fall back asleep for another cycle through these stages. They are then woken up after the cycle completes itself and so on. . .

White Noise

your little one starts to experience lighter stages of sleep, they can be more easily awoken. Noises are more likely to wake your baby up during these lighter stages of sleep and we don’t want that. White noise machines help to block out external noise so that your little one can stay asleep for longer. Read all about white noise here

Other Skills

All sleep regressions coincide with a newly learned skill such as rolling. Your little one is SO excited to practise their new found skills that they want to practise All. The. Time. Even in the middle of the night or when they are supposed to be napping. My advice to you is to 1) take a deep breath 2) remind yourself that this is temporary 3) practise practise practise. The more your little one practise their new skills the sooner they can master the skill and the novelty will wear off. I recommend using the crib culture sleep suit if your little one is waking up because they can roll onto their stomach but cannot get back onto their back. This sleep suit prevents rolling in the first place! It is also a wonderful transition out of a swaddle. Read more about swaddles and sleep suits/sacks here

How Long Will This Last?

Unlike other regressions, the 4 month sleep regression is not necessarily temporary. Why? Because is it not just a phase, but rather the maturing of their sleep cycles. Sleep regressions look different for every baby and on average they last 2- 6 weeks. This may sound daunting but fear not! With some sleep training, your little one can learn how to self soothe and fall asleep independently! Falling asleep independently is a skill your child will need for the rest of their lives! You are teaching them a valuable skills that they will use forever. I work with families one on one to help them teach their little ones these skills. Contact me to find out how I can help you.