Breaking Down the 4 Month Sleep Regression

Photo by Colin Maynard on Unsplash

In the beginning, most babies sleep. A lot. Of course, with just about any scenario, there is always a few exceptions to the rule, in this case, having a newborn that doesn’t sleep much at all. However, for the sake of the topic of examining the 4 month sleep regression stage, we will focus on the babies that slept a lot the first 3 months of their lives, to all of a sudden, not sleeping well at all.

Many parents chalk this up to a sleep regression, as if it’s a way to explain why a child, that had seemingly mastered a skill, isn’t quite so good at it anymore. However, a question I like to ask parents who label their child’s sleep struggles as a regression is, “If your child had been doing so well and “practices” sleeping every day, how would it work that their sleep would get worse?” 

Is it possible that it's not a regression after all? What if I told you that it is actually a sign of transition?

What generally comes out in the end, is the realization that their child didn’t have independent sleep skills. It also means that their child was undergoing some incredible changes when it came to sleep. In the beginning, biology was running the show, but as the baby matured and grew over the next four months, biological instincts become less intense and influences of the surrounding environment starts to take over. If the child was relying on external forces, known as sleep props/crutches/associations, such as rocking, nursing, or swaddling, to help them sleep before the 4 month sleep regression hit, then their reliance on sleep props only becomes greater and sleep then begins to suffer.

What's the Big Deal About 4 Months?

In the beginning, babies cycle between two stages of sleep, known as “active” (REM) and “quiet” (non-REM) sleep. They do not experience the distinctive sleep stages that older children and adults do, where we cycle through four distinct sleep stages within non-REM before entering REM. As a result, newborns spend much of their time in deep sleep. This would explain why it’s hard to wake them up to eat, or why they sleep through loud noises happening in their environment and can sleep through the motions of being passed around by caregivers. However, as they transition from quiet sleep to active sleep, they can startle themselves awake, which is why swaddling is encouraged the first eight weeks of life.

As the baby approaches four months of age, their brains start to mature and their sleep patterns change. Instead of moving back and forth between REM and non-REM, they now start adding in the four distinctive sleep stages that occur within non-REM sleep. Adults typically cycle through these stages, including REM, every 90-100 minutes, leading to brief moments of wakefulness/light sleep that occur multiple times every night. Babies will cycle through these stages every 45-50 minutes, meaning that their brief moments of wakefulness/light sleep occur more often every night. To do the math on timing, this would mean that if you were rocking your baby to sleep every time, you would have to do this for about 30 minutes to ensure that your baby is in deep enough sleep to lay them down, and then they may wake up in 15 minutes anyway and you’d find yourself facing the same predicament all over again.
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With babies who rely on external influences/supports to fall asleep, they will be looking for that support every time they wake up, leading to the baby and the parents experiencing full-on wakings multiple times a night, every night. 

​Sleep Patterns Explained

In technical terms, if your baby is able to connect 5-6 hours of sleep without needing to feed, then they are “sleeping through the night”. Most babies will be able to do this by 8-12 weeks of age. The beginning of the night is where sleep drive is highest and the deepest sleep for your baby occurs. Their melatonin levels are spearheading the sleep drive, and cortisol levels are usually at a low. After 5-6 hours, sleep will not be as deep, as melatonin levels start to drop off. This is where the problem with sleep crutches become painfully obvious. If the baby needed their sleep prop to fall asleep at the beginning of the night, then sometime after 5-6 hours, they will continue to need that sleep prop every 1 – 2 sleep cycles, which would work out to be around 45-90 minutes every time.

In between the hours of 4:00 and 6:00 AM, melatonin levels are at their lowest, making this time of the night to be where the lightest sleep happens, and many parents report that their baby will wake up for the day. If the baby manages to sleep fairly well through this period of time, or wake for a single feed and go back to sleep, they will generally experience one more deep sleep cycle before waking up for the day.
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However, if the child “wakes up” for the day in between 4-6 AM, many parents report that within 30 minutes to an hour after waking up, their child seems ready for a nap. In this scenario, it is actually a case of where the child was experiencing a night waking, not an actual waking for the day. This is often referred to as a holdover from the night before. 

​As Babies Get Older, Sleep Becomes a Needed Skill

Before biology’s influence lessens, it is important that a child has the opportunity to gain and practice independent sleep habits, where they practice putting themselves to sleep on their own. Sleep skills are highly individualistic and everyone, even the 8 week old newborn, needs to have a chance to develop their own without outside influences. When given true opportunities to develop and practice independent sleep skills, babies have the capacity to take those opportunities and use those moments to learn how to become good sleepers and overcome development milestones and sleep challenges, even when the dreaded 4 month transition stage tries to come and visit. In this case, true practice, makes perfect. Truly.
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If you have been hit hard by the 4 month regression/transition and it shows no sign of getting better, I can help you teach your child overcome the challenge and become a great sleeper in just a few weeks. Set up your free 15 minute phone call today to get your sleep evaluation and learn how I can help.