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4 Month Sleep Regression

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Cara Dumaplin

awake baby 4 month sleep regression

What is the 4 month sleep regression?

At about 3-4 months of age, our babies can begin to struggle with sleep even if they seemed to be good sleepers before this time.

Why does the 4 month sleep regression happen?

At around 4 months, babies move from the newborn phases of sleep into more adult-like sleep stages. 

Let me explain how this causes trouble. Adult-like sleep stages string together into “sleep cycles.” These cycles last 60 -120 minutes during the night. After each sleep cycle, your baby’s body will come to light stage of sleep and often slightly awaken. He will check in with his environment, making sure that everything is okay and his surroundings are unchanged. See the chart below to understand what this looks like over the course of the night:

graphic of sleep cycles for babies

For some babies, each slight awakening turns into a major struggle. These babies usually fell asleep in mom or dad’s arms, at the breast, or being rocked. Let’s play out that scenario: Perhaps your baby fell asleep in mom’s arms and then is set down in the bassinet when she’s fast asleep. After about 60, 90, or 120 minutes, she will awaken and check in with her environment. Guess what her little body says during the check in: “Hey, this isn’t right! My surroundings are different. I was in Mom’s arms when I fell asleep. Where am I now? In this cool, flat bassinet! Waaaaaa! Mama, come get me.” (Can you blame her? What if you fell asleep in your bed and awoke a few hours later in a different bed? Wouldn’t you freak out and cry?) Our bodies expect our surroundings to be unchanged during these wake-ups.

So, what do parents do when our babies cry in the night? Well, we often assume they must be hungry, so we feed them and they fall back to sleep. Now, they’ve entered this new stage of sleep cycles, so one to two hours later, they are awake again. We convince ourselves that they must be having a growth spurt. We offer another feeding. Then 1-2 hours later… awake again! A few nights of this, and now, their little bodies become accustomed to this frequent waking. This is the beginning of sleepless nights called “the 4 month sleep regression.”

During months 3 and 4, our babies also become aware of the big world around them. During the day, they suddenly notice big brother playing with toys, the dog running around the room, the light from our cell phone flashing, and all sorts of other exciting happenings in the environment that before was just background noise. All of these things are WAAAAAY more interesting than eating. So our babies naturally get shortened, smaller feedings as they become more distracted by this exciting, big world.

Couple that with all the extra feedings baby received last night, and there’s really no reason to eat well today. Right?

So, guess what happens tonight? He awakens every 1-2 hours in accordance with these new sleep cycles, but he’s genuinely hungry because he didn’t eat much during the day. This creates a cycle of night wakings with multiple feedings due to poor (or not-so-great) daytime feedings. If you’re struggling with this problem of getting a large majority of the calories in at night, this is called “reverse cycling.” 

Can you see how these new developmental changes with sleep cycles and your baby’s understanding of the world can turn into a big struggle with sleep at night?

What week does the 4 month sleep regression start?

We can start to see babies experience the 4 month sleep regression as early as 13-15 weeks.

How long does the 4 month sleep regression last?

The sleep cycle transition usually only takes a couple of weeks. But…I have good news and bad news. 

The bad news: The effects of this transition, like the more frequent wakings your baby has adjusted to and the reverse cycling, can last for a long time if you don’t have a plan to get on track (or back on track). Your baby is unlikely to magically start taking in most of her calories during the day if you’re feeding her every hour or two all night. Independently falling asleep at bedtime and back to sleep in the night are skills that don’t just appear: they have to be learned.

The good news: The effects of the 4 month sleep regression don’t have to last for long!! The 5-24 Month Collection can be the plan you need for having a great little sleeper in just a few short weeks. You can get started as soon as your baby reaches 5 months. Think 10-12 hours of independent night sleep in the crib, a plan for naps with a flexible routine that works for your family, and a baby who gets what she needs to have great days and nights.

Can I prevent the 4 month sleep regression?

You can’t prevent the developmental changes that often result in this 4 month sleep regression. HOWEVER, there are things you can do to help set your baby up for an easier experience with the transition.

My First Five Months Bundle teaches you how to gradually work on setting your baby down to fall asleep on his own at bedtime and transitioning through sleep cycles more independently (with NO crying). If your baby knows how to put himself to sleep in his own crib/bassinet, this 4 month sleep regression doesn’t have to feel so scary. Think about it this way: when he hits a new sleep cycle, awakens slightly, and looks around, he knows his bassinet and knows how to put himself back to sleep. 

Some babies sail smoothly through this regression because of the skills they have already been practicing. Other babies have a harder time with this transition. If you are struggling, please know you’ve done nothing wrong. Even the best of sleepers can struggle during this time. Any practice you’ve done with these skills before and during the regression will make sleep work in the future easier.

Can you do cry-it-out during the 4 month sleep regression?

I don’t recommend any formal sleep training until your baby is 5 months.

My goal is always to help you meet your baby right where he is developmentally. During the 4 month sleep regression, there is so much development that is taking place with your little one's awareness of the world, sleep cycles, and physical growth. Those who attempt to sleep train before about 5 months often find that sleep training involves much more crying, much more struggle, and many more days to see success. Hear my heart: I do not want that for you or your baby.  

Once your baby has reached 5 months (or very nearly 5 months), the sleep cycle adjustment has been made and the melatonin hormone required for successful sleep also begins to regulate, making sleep training much more effective. Please know that when you ARE ready for sleep training, you don’t have to figure it out on your own or simply let your baby “cry-it-out.” Instead, let me walk alongside you and teach you everything you need for great sleep with The 5-24 Month Collection. I’ll show you how to customize a sleep plan that works for your baby and your family’s values. (That’s right: it doesn’t have to include cry-it-out at all.)

If you’re in the thick of this and you know you need to wait until 5 months for sleep training, I’m sure you’re now thinking: 

How do I deal with the 4 month sleep regression?

1. Recognize the change in sleep cycles around 4 months of age.

The sleep cycle change that can cause a 4 month sleep regression happens for every single baby. For some, it is a smooth transition. For others, it can cause some bumps in the road. Prepare your mind that it will happen, but don’t let it scare you!

2. Try to put your baby down awake at bedtime.

If you’re thinking “yeah, right, not my baby,” Navigating Months 3 & 4 can help you slowly work toward this goal by giving you practical steps to make progress until you’re ready for sleep training with The 5-24 Month Collection.

3. Maintain adequate feedings during the day.

Continue offering feedings every 2.5-3.5 hours during the day according to your baby’s hunger cues. Remember, the 4 month sleep regression can turn into a reverse-cycling problem if your baby isn’t getting in those good feedings during the day.

4. Begin to expand wake windows.

Getting good awake time during the day will help set your baby up for good naps and night sleep. Your goal wake windows at 4 months are 90-120 minutes. 

For help with expanding those wake windows and knowing how to use your days to help prepare your baby for better nights, download my free guide called 5 Daytime Tips for Better Nights (and Naps!).

5. Consider using a transitional product for coming out of the swaddle.

Many babies at this age are rolling or showing signs of rolling. That means it’s time to transition out of the swaddle for safety. If this feels scary to you, a transitional item like the Swaddle Sleeves Sack (code CARA10 saves 10%) or Merlin’s Magic Sleep Suit can help.

6. If by around 5 months of age your baby isn’t sleeping through the night, know that you don’t need to struggle any longer.

The 5-24 Month Collection will walk you step-by-step through a completely customizable, holistic sleep training experience. In just a few weeks, your baby will be getting 10-12 hours of independent night sleep, AND you’ll have a plan to navigate any future regressions or bumps in your journey. I’ll also help you set up a daytime routine and nap schedule that fits your family’s lifestyle and values. And you’ll get age-specific guidance to meet your baby right where he or she is developmentally at every stage from now until your baby turns 2.

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