4 Month Sleep Regression

Sleep regressions are very common for every child but can be very difficult for a child who is already not sleeping well. The 4 month sleep regression is one of the biggest regressions your child will go through. But it’s actually a good thing.

Learning more about how newborns sleep can help explain a lot of what you are about to, what you’re going through, or already did go through. Unlike all the other regressions there is a major change going on in that little body for the 4 month sleep regression. But I like to think of this more as a PROgression, not a regression.


What’s going on during the 4 month sleep regression? More sleep cycles!

Unlike older children and adults, newborns are born with only 2 sleep cycles. Around the age of 3-4 months is when they begin to develop the ability to sleep longer stretches and also develop the 4 sleep cycle pattern they will have the rest of their lives.

The 2 sleep cycles newborns are born with are Rapid Eye Movement (REM) sleep cycle and Non-Rapid Eye Movement (NREM) sleep cycle. During REM sleep you can expect to see your baby’s eyes flutter (while staying closed), or arms and legs twitch. This is also known as active sleep. NREM sleep, also known as quiet sleep, is when your baby is sleeping very still. 

* https://www.sleepfoundation.org/baby-sleep/baby-sleep-cycle

After that 3-4 month age, newborns develop the other two NREM sleep cycles, giving them 4 sleep cycles in total. And not just any two new sleep cycles, they now have gained the two lightest sleep cycles, hence the 4 month sleep regression…


1st Stage NREM – lightest sleep stage

2nd Stage NREM – another light sleep stage

3rd Stage NREM – deepest sleep stage, very hard to be woken

4th Stage REM – sleep stage where dreams occur


This means that the baby who you took to the town parade and slept through the entire thing, is going to have a hard time doing that same thing at an older age. Think about it, they spent the first couple months of their lives with only two sleep cycles which were the deepest two sleep stages. Now only 50% of their sleep is spent in those stages while the other 50% is spent in the two lightest stages. 

See it’s not the 4 month sleep regression, it’s actually a PROgression!


How to get through the 4 month sleep regression

Here is the part you really came here for, what can you do to best get through this change for you and your family. 


I know your child is young, but a good routine establishes healthy habits. A bath, zipping up a sleep sack, the same lullaby sung are all cues that your child will begin to pick up on knowing that sleep is coming.

A routine also allows them to get in a restful state encouraging good sleep to come. Have  4 or 5 steps. The routine should be about 20 to 30 minutes. Make the feed for the night the very first step. This will prevent any association between eating and sleeping. 

Avoiding a feed to sleep association doesn’t mean I don’t want you to feed your baby. At this age your baby needs to feed and probably again in the middle of the night. But what you want to do is allow your baby to wake up on their ownasking for a feed and just a feed.

If your child is used to falling asleep while eating then when they wake in the night it may not be because they are hungry but because that is the only way they know how to get back to sleep. 

Awake windows

At 4 months old the appropriate awake window is about 2 hours. This means two hours from the time they wake up in the morning to the first nap, first nap to second and so on. 

If you are over or under this awake time, your baby could be over or under tired. Under tiredness is less common, but essentially your child needs to play more. Build up more sleep pressure to help the transition to falling asleep.

If your child is overtired, then even though they are tired and want to goto sleep their body isn’t letting them. Overtiredness creates a secretion of cortisol, which feels like an adrenaline rush. Making it very difficult to fall asleep. Avoid this by watching the clock each time they wake.

*This will mean your baby’s schedule from day to day may be slightly different. It’s not until babies are about 8/9 months old that they are on a set time schedule. 

Make the room dark 

At the age of 3/4 months, your baby has their day and nights figured out. This means they no longer need a little light let in during naps to establish the difference between day and night. Now you want to completely blackout their room. Each time they are in their crib, you want their room to look like it does at midnight.

Remember those two new sleep cycles they just grew into? Well when they come to the top of each sleep cycle they are in the lightest stage of sleep. This is where the majority of us wake up, it’s normal. We just know how to go back to sleep. Your baby is learning. So if it’s too light in their room, the light will wake your baby up even more to the point where they can’t get back to sleep.

Independent Sleep

This is the key to beginning a healthy foundation. As a newborn, you probably laid your baby down drowsy, great. But now is the age where you want to lay your baby down completely awake. I don’t mean ready to party awake, I just mean they need to be aware they are being put in their crib.

You can feed, hold, rock, and comfort your baby, of course! But you don’t want to do those things until they fall asleep. If you do, they will begin to get drowsy. Drowsy is stage 1 sleep, and if your child gets startled when you lay them down, meaning you woke them up, they just got a little sleep and now their body will fight sleeping more until it’s ready.

The other reason for independent sleep, is again those two new light sleep stages they now have. Like I said, this is the top of the sleep cycle and where you and I wake up. We know how to roll back over and go back to sleep. Sometimes we remember, sometimes we don’t. These are naturally occurring wake ups.

For your baby, they are learning how to “roll back over” and go back to sleep. But if they didn’t put themselves to sleep at the beginning of the night, they won’t remember how to do it again during the night. And then they will call for you because they want to go back to sleep but need you to do it for them.

You want some noise

By noise I mean a sound machine. While your baby is now spending 50% of their sleep in light sleep stages, light can interfere with their ability to stay asleep. A sound outside during nap time when they were newborns wasn’t an issue because they only slept in deep sleep stages. Now, that same sound may startle them awake.

When using a sound machine it doesn’t have to be really loud, just loud enough to drown outside noises out. Put it about 5-6 feet away from your baby’s crib. Make sure it plays continuously, if it turns off after an hour then this sound change can wake them up as well. I’m also a big fan of just white noise/ static where there is no change in sound. So keep it constant and keep it on.


I know, it is easy to give up on a process after just an attempt or two. It’s important to know this process can take time. Practice. If you told me your child woke up 5 times last night, but just once they put themselves back to sleep. I will throw you a party. That is great news!

THIS is what you need to continue to build upon. Creating the same scenario each time during the night and at nap time is imperative to your child learning this skill and doing so quickly. 

Now I’m not saying your child can sleep through the night at this age. Most babies still need to wake up for a feed. But after the feed is another time you can practice these skills with your baby. 


A gift to give them

Getting through this regression, or progression won’t be a quick fix. Some babies will take to these changes very well and some may not. Either way, knowing when your child needs to go to sleep and allowing them to do it without any external help are all healthy habits. Healthy habits will continue to grow, giving your baby a healthy sleep foundation they can build upon.

For those of you who have a baby who seems a little more resistant to this change, visit my website or give me a call. We can work together on a more personalized plan. Don’t wait too long, I hear too often “I wish I did this sooner.” 

I offer a free 15 minute call where we can just chat about what is going on and I can give you all the details on what working with me looks like. How to best support you. And most importantly how to establish that healthy foundation for your child.