Understanding and Managing the 4 Month Old Sleep Regression

by | Oct 8, 2020 | Blog, Famous Sleep Regressions, Podcast, Sleep Challenges | 0 comments

BONUS MATERIAL: If your little one is going through the 4 month old sleep regression (or ANY regression for that matter) that doesn’t seem to end, watch my FREE sleep masterclass where I will show you how to get your little one consistently sleeping 11-12 hours at night and napping like a champ, even if you feel like you’ve tried everything!

If you’re finding yourself saying “Hey- why is my baby suddenly REFUSING to sleep?”, keep reading as he might be experiencing the dreaded 4-month sleep regression.  Perhaps for the first 3-4 months of your baby’s life, you were able to peacefully rock her to sleep and expect longer stretches between night feeds.  But all of a sudden, it’s taking you hours to rock her to sleep, and she’s waking up countless times a night.  

You take your cranky and miserable baby to the doctor to rule out an ear infection, making you wonder if your baby is teething? (*spoiler alert- he’s not!)

The reality is that your baby is likely experiencing the 4 month sleep regression.  As a pediatric sleep expert for babies and children, I have exhausted parents reaching out to me when their baby is in the throes of this regression ALL THE TIME!  

In this blog post, I will delve into what the 4-month sleep regression is, what causes it, and most importantly, how you can address it effectively. Understanding this phase and knowing how to navigate through it can help you and your baby establish healthy sleep habits and get yourself a champion sleeper. So, let’s dive in!  

What IS the 4 month old sleep regression and what’s really happening?  

The background

The 4-month sleep regression refers to a disruption in a baby’s sleep patterns around the age of 4 months (sometimes earlier).  During this regression, your baby experiences big neurological changes as he transitions from newborn sleep patterns to adult-like sleep cycles.  I prefer to look at this regression as more of a PROgression because it marks a permanent change in your baby’s sleep habits as he gets older.  

See, when your baby was a newborn, his sleep was much more ‘babyish’- meaning, he slept deeply all the time!  This probably explains why he was able to sleep anytime and anywhere, regardless of noise and distraction.  

Once your baby hits that 3.5-4 month mark, your baby’s sleep patterns mature and become more ‘adult-like’ where he begins to cycle in and out of deep and light sleep.  Your baby is no longer a newborn!  

The not-so-great news is that this milestone often causes tons of night wakings and short naps for 3 main reasons:  

1) If your baby doesn’t know how to fall asleep on his own and relies on a sleep association or crutch to fall asleep, he’ll suddenly need help falling BACK asleep at the end of that 45 minute sleep cycle.

2) A typical infant sleep cycle is only 45 minutes-long and primarily consists of light, REM sleep.  This shift can cause babies to wake up more easily during the night and experience difficulty falling back asleep independently.

3) At around 4 months of age, your baby’s brain undergoes significant development and other changes, including increased awareness of their surroundings and improved motor skills. These advancements can make it harder for them to settle down and fall asleep.

Your baby’s new sleep cycles

Take a look at this image of a typical infant sleep cycle to get a better idea of what these new sleep patterns look like.

illustration of baby's sleep cycle every 45 minutes

During the first 5-10 minutes of this sleep cycle, your little one falls asleep and is in very light sleep.  By the 10-15 minute mark, she transitions to slightly deeper sleep.  By the 20-30 minute mark, your little one is in the deepest sleep of the whole cycle. But guess what? By the 30- 40 minute mark, your little one is already transitioning from deep sleep to lighter sleep again! And then by the time you get to that 40 to 50 minute mark, the sleep cycle is over.  

At the end of that sleep cycle, one of two things is going to happen.  Either your little one is going to put himself back to sleep or he’s going to wake up. But if your little one does not know how to fall asleep independently to begin with, there’s a higher likelihood he’ll wake up because he’ll struggle to consistently putting himself BACK to sleep on his own, even if he wants to.

While this regression can be challenging, it’s important to understand that it’s a normal part of your baby’s development- for better or for worse!

Signs that the 4-month sleep regression has hit

Recognizing the signs of the 4-month sleep regression can help you differentiate it from other sleep-related issues. Some common symptoms include:

  • Difficulty falling asleep.  Your baby might start resisting bedtime and struggle to fall asleep easily.
  • Frequent night wakings. Your baby may start waking up more frequently during the night, requiring your presence to soothe them back to sleep.
  • Shorter naps. Previously longer naps may become shorter, leaving your little one feeling overtired and fussy.
  • Increased irritability: Due to insufficient sleep, your baby may become irritable and fussier during the day.
Tired mom of a 4 month old baby

The regression has hit!  Now what?  

With most sleep regressions, life should go back to normal within a few days, up to 1-2 weeks, as long as your baby had healthy sleep habits beforehand.  The 4 month-old sleep regression, on the other hand, is different. Unfortunately, this is not a phase that will magically go away over time.  The changes to your baby’s sleep patterns are permanent so waiting-it-out for things to magically improve is NOT advised here.  

This regression requires action!  

Here are some practical tips and insights to help you survive this regression and get your sleep back:

Teach your little one to sleep independently with sleep training

Teaching your baby to sleep independently, also known as sleep training, is the the best way to improve sleep quality and eliminate unnecessary nightwakings in the short term, as well as in the long run.  If your little one’s sleep has regressed during this regression, teaching him how to connect his sleep cycles independently is crucial.  It allows your little one to learn to put himself back to sleep on his own (the way that you and I do at the end of OUR sleep cycles) and not wake up to begin with! 

**If you and your baby are both “falling on your face” exhausted and you’re feeling ready to get your baby sleeping amazingly…but you have no idea where to start, check out my free sleep masterclass here (or click the image below to sign up)**.

Free sleep masterclass 4 month old sleep regression

An important note about sleep training a 4 month-old

Contrary to popular belief, four months is not too young to begin sleep training. However, there ARE misconceptions surrounding the topic that need to be clarified.

Firstly, while nighttime sleep training is very doable at 4 months-old, it doesn’t mean your 4 month-old is ready to be completely night weaned. Sleep training and night weaning are not the same thing. Night weaning involves gradually reducing nighttime feedings, while sleep training focuses on teaching your baby to fall asleep independently. It’s important to understand that sleep training doesn’t necessarily mean removing all night feeds, as many babies in the 4-5-month range still need one or two feeds per night.

Second, sleep training does not need to involve leaving your baby to cry it out. There are various sleep training methods that provide support and comfort to your baby while teaching them to sleep independently. Checking on your baby at specific intervals or utilizing a gradual withdrawal method are two examples of approaches that allow for a supportive sleep training experience.

Sleep training is not a one-size-fits-all solution.

That being said, if you continue relying on sleep crutches or props during the night, your baby’s sleep issues are likely to continue. Without the ability to fall asleep and stay asleep independently, your baby may continue to wake frequently during sleep cycles, requiring your help.  And that’s exhausting!

​Other tips for managing the 4 month sleep regression

  1. Make sure the sleep environment for your baby is optimal for good quality sleep. Blackout curtains (like these ones), a white noise machine (like this one), a sleep sack (like this one) and a cool, comfortable room temperature are all a must.
  2. Ensure that your baby is napping frequently during the daytime and that your little one’s wake windows aren’t bigger than 1.5-1.75 hours.  Respecting your little one’s nap schedule allows you to avoid having an overtired baby. **If you are unsure of your baby’s sleep needs, you can download my free sleep chart here that has a detailed breakdown of all my suggested wake windows, nap totals and sleep totals for babies ages 0-5!**
  3. Make sure your baby is getting full feedings during the daytime. If you are nursing, make sure you are feeding your baby on demand, every 2-2.5 hours.  There is often a growth spurt around this time so you want to make sure your baby is well fed!
  4. It’s usually not a good idea to wean from all night feeds. The vast majority of babies this age still need to eat 1-2 times a night.
  5. Establish a bedtime routine. A consistent bedtime routine signals to your baby that it’s time to wind down and prepares them for sleep. Activities such as a warm bath, gentle massage, and reading a book can make it easier for your little one to fall asleep.

There is hope!

If your baby is currently going through the 4-month sleep regression, there IS hope for improvement- don’t despair!  Teaching your baby to fall asleep independently, along with implementing those additional sleep tips, can make a SIGNIFICANT difference.

For example, a mother who joined my Sleep Bible program had a 4.5 month-old baby going through the 4 month regression and was waking up around 20 times a night! Through implementing a sleep plan that helped her baby learn to connect his sleep cycles independently, he quickly started sleeping through the night with only one feed!

My daughter’s disastrous 4 month old sleep regression

I have my own personal example of a disastrous 4 month regression that was resolved with proper, holistic sleep training.  When Eliana, my middle child, was 4 months old, she suddenly started waking up every 45 to 90 minutes all night long, needing me to reinsert her pacifier to help her go back to sleep.  I was so tired that I honestly thought I was seeing stars. 

See, Eliana was a baby who relied heavily on a pacifier to fall asleep and stay asleep. It wasn’t a problem in the newborn stage because she wasn’t aware enough to realize when the pacifier had fallen out.

But once Eliana reached that 4 month mark and was much more aware of her environment and her surroundings, she became aware of when the pacifier fell out (which was pretty often).  When she started waking up VERY frequently throughout the night, it left me no choice but to remove the pacifier from the sleep equation completely and teach her how to sleep independently without it.  

And I’m telling you, it was an absolute game changer.  She started sleeping through the night (with one feed) I got my life (and sanity) back!

A quick word about my Sleep Bible program

You know how “they” say that everything happens for a reason? Well, my sleep woes with Eliana are precisely what inspired me to launch My Sleeping Baby as a side business. This business grew quickly into a full-time thing that I left my career as a lawyer to do…and haven’t looked back.

My Sleep Bible program (inspired by Eliana herself) is your one-stop shop to get your baby, toddler or preschooler consistently sleeping through the night like a champ so that everyone in your family is finally well-rested. With a tailored plan customized for YOUR little one, we can REALLY figure out what works for them and get their sleep issues resolved…for good! Afterall, he’s a baby, not a robot!

Your can learn more about my Sleep Bible while watching this free sleep class here.

Sleep bible course

My favourite products for your baby’s sleep environment

Here’s a list of some of my recommended sleep gear for your little one’s room:

*I may earn a commission from links on this page at no additional cost to you, but I only recommend products I love.


To sum up, the 4-month sleep regression is not a phase to wait out or ignore. Rather, it signifies a PERMANENT change to your baby’s sleep patterns as they transition from newborn to adult sleep cycles. It’s crucial to help your baby develop self-soothing skills so they can consistently connect sleep cycles and avoid unnecessary nightwakings.

Remember that sleep training does not require removing night feeds or leaving your baby to cry it out. It IS possible to sleep train your four-month-old while maintaining night feeds and providing supportive guidance.

Maintaining healthy sleep hygiene for your little one in the form of an optimal sleep environment, frequent daytime naps and feeds, and a relaxing, consistent bedtime routine is equally important when your little one is experiencing this regression. 

By understanding and addressing the sleep issues surrounding the 4 month regression, the good news is that you can show that regression the door and REALLY convert your baby or child into a champion sleeper for life.

Want to get your little one consistently sleeping 11-12 hours at night so you can be a functioning human?

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