Key Points:
- Sleep cycles have developed and are now longer: 90 minutes. They also go through 4 sleep stages instead of just 2.
- Cognitive development: Increased curiosity and awareness keep babies from falling asleep.
- Motor development: Increased mobility and the urge to practice before bedtime makes falling asleep challenging.
- Babies go through a growth spurt at 3-4 months, causing more wakings to supply their calorie demand.
Oh, the 4 month sleep regression! It marks a before and after in the lives of new parents who hear of this term for the first time. “My baby woke up like 10 times last night! She was finally down to just a couple night wakings and now this!” says a new mom to her more experienced mom-friend. “It must be the 4 month sleep regression!” she responds. “The 4-month what?”. And so here you are, reading about the 4 month sleep regression.
It’s actually one of the most popular of all sleep regressions (yes, it’s not the only one). It presents itself when babies have just begun sleeping better at night, giving their parents a break from those awful newborn nights. In this sleep regression, babies have more frequent night wakings, they struggle to fall asleep and may have shorter naps during the day. But, rest assured, it’s just temporary! The 4 month sleep regression goes hand in hand with significant developmental changes babies undergo at around this time. Lets dive in!
Development of Sleep Cycles
When babies are born, they have short sleep cycles that last around 50-60 minutes and only go through 2 distinct sleep stages: Rapid Eye Movement (REM) and non-REM (NREM). As they approach the 4 month mark, these cycles become longer, now lasting around 90 minutes, and reach the same 4 stages of sleep as adults do: NREM 1, NREM 2, NREM 3 and REM. Although they begin to go through all the same stages, the order and duration of each stage doesn’t quite mirror that of an adult just yet; that happens at around 5 years old. When babies start to go through these 4 stages at 4 months, their bodies have a bit of difficulty transitioning between them, and hence their more frequent night wakings during the night or perhaps difficulty falling asleep on their own.
Cognitive and Motor Development
Babies go through some major leaps in their cognitive development at around 4 months. Their improved vision, longer wake windows and increased mobility have allowed them to become more aware of their surroundings. They are now more alert and interested in interacting with and exploring their world. All of this new mental activity and stimulation interferes with their ability to fall asleep or even stay asleep.
You’ll notice now that when it’s their time to fall for a nap or bedtime, their eyes are wide open, they twist and turn to look towards something that catches their attention or they become extra alert if they hear a sudden sound. During this sleep regression, many parents begin to put a bit more effort into preparing a darker and quieter sleep environment to help their babies wind down.
Increased mobility is also another factor that can affect babies ability to fall asleep or go back to sleep. Most babies are now pushing up during tummy time and rolling over, and some are even trying to sit up. As they work on these skills, they want to practice even during night time! And sometimes they’ll even roll over in their sleep unintentionally and wake up because of it! You might notice the first time your baby rolls over is during sleep. You’ll know because you set them down on their back and when they wake up, they’re on their tummy! It’s exhausting but quite exciting too!
Growth Spurts
Growth spurts are a period of faster-than-usual growth in a baby. Babies grow a little each day, but during a spurt, which can last one to a few days, the growth happens at a much faster rate. Babies have these in many moments of their life and one of them happens to occur between the 3 and 4 month mark. These spurts come with an increased demand of calories for growing and so they typically wake up more often at night to supply that demand. They might also need extra comfort from their caregivers and both of these needs take part in disrupting a baby’s sleep patterns.
To sum it up, babies go through their first sleep regression mainly due to their development. So many new milestones and stimulation, parallel to a maturing and changing sleep architecture is what causes this sudden change in sleep. While it can be a tough time for both babies and parents, it’s important to remember that this regression is temporary. Babies typically return to more regular sleep patterns after adjusting to their new skills and routines. Offering comfort, consistency, and patience can help during this challenging phase. Now that you know and understand the reasons behind this sleep regression, navigating these days will be a bit easier!
