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4 Month Sleep Regression Explained (sometimes 3 and 5 months too)

4 Month Sleep Regression

Over the years, our team has seen countless parents come to us for help with their 4 month old babies sleep. Why? Simple – it’s the 4 month sleep regressionThis article will explain why “good” sleepers sometimes turn “bad” around the 4 month old mark, also known as the 4 month sleep regression. For most babies, the 4 month sleep regression occurs right around the 4 month mark, but for some babies, it happens a bit earlier (around 3 months) or a bit later (around 5 months). For some babies, the 4 month sleep regression is relatively mild and very brief; for others, the 4 month sleep regression is a very, very rough phase marked by lots of crying, and that lasts pretty much indefinitely.

4 Month Sleep Regression: How Your Newborn Baby Sleeps In The Early Weeks

Yes, this is an article about the 4 month sleep regression, so we really should be talking about 4 month old babies, right? We will, in just a moment – but first, we need to back up to the newborn phase. When a newborn sleeps, she cycles between “active” and “quiet” sleep (also known as REM and non-REM sleep), but does not have the distinctive stages of sleep she will have as she grows older and her brain matures. We’ll avoid too much technical talk (that’s one reason we have this website, so you won’t have to learn the whole history of sleep if you don’t want to (or can’t stay awake to!), but if you are interested in knowing more about our biological rhythms and how we do sleep in more detail, I highly recommend the book, Solve Your Child’s Sleep Problems), even if you have no interest in “Ferberizing” (just skip that part and consider a no-cry method). Newborns spend a lot of their time in deep sleep, which is why it is hard to wake them up (even to eat!) in those early days, but they do startle when they cycle into “active” sleep, which is one reason swaddling your baby can be so effective.

The 4 Month Sleep Regression Changes Things: How Your 4 Month Old Baby Sleeps (And Sometimes Your 3 Month Old Baby, or 5 Month Old Baby)

We all go in and out of light and deep sleep. As adults, we might change positions, look at the clock, or reposition our pillow. Up until now, you may have rocked your baby or simply given him a pacifier and he slept for hours without waking up. Well, at 3 or 4 months old, your baby is now sleeping more like an adult. Now when she falls asleep, she does not enter deep sleep right away, and if you lay her down before she is in deep sleep, she is likely to wake up and you will start all over helping her to fall back to sleep again and again.

4 Month Sleep Regression Patterns: First, Your 4 Month Old Baby Enters Deep Sleep…

Initially in the night, your 4 month old will enter deep sleep relatively quickly, within 30 minutes (this changes as we get older). However, as I said, we all cycle in and out of light and deep sleep. A child’s sleep cycle is about 45-50 minutes. So, your baby will briefly awake 45-50 minutes after she has been asleep. To put that in perspective, if you are holding your baby to sleep, you would need to hold her for at least 30 minutes to make sure she’s in deep sleep and then she might wake up 15 minutes later. Sound familiar?

Overall, though, your baby’s deepest sleep is in the early part of the night, so after that first sleep cycle, she might sleep just fine for a few hours. So, you’re golden right? Just hold her for an hour? Nope!

4 Month Sleep Regression Patterns: How Your 4 Month Old Baby Sleeps The Rest Of The Night…

The technical definition of “sleeping through the night” is 5 hours of continuous sleep (i.e. no feedings) and many babies can/will do this by 2 or 3 months old. The beginning of the night is your baby’s deepest sleep, and after the first 5 hours (if not sooner, depending on just how challenging he is), he will cycle between light and deep sleep, but the deep sleep won’t be as deep as it was at the beginning of the night. This is where the problem of sleep associations really come into play. If your baby needs your help to go to sleep in the beginning of the night, sometime after midnight or so, he will continue to need your help every 1 or 2 sleep cycles (that means every 45 to 90 minutes, or as I often hear, every 1-2 hours).

Between 4-6 a.m., approximately, is the lightest sleep of the whole night (parents’ complaints alone make this true, in my experience, aside from my reading). In the very early morning hours (about 30 minutes to an hour before waking up), he will again go into the very deep sleep.

Although babies commonly wake up early, be sure it is truly their waking up time and not just this lighter sleep and that they are having trouble sleeping. You might notice they want a “nap” just 30 or so minutes after “waking up”. What you experienced was a night waking, not starting the day.

4 Month Sleep Regression Symptoms

Many parents want to know what the 4 month sleep regression looks like. That will vary from baby to baby, of course, but here is a short list of 4 month sleep regression signs:

  • Changes in appetite (baby may eat more or less than usual)
  • Lots of night wakings (these will seem out of the ordinary, especially if your baby had been sleeping longer stretches recently)
  • Increased crying and fussiness (often, the fussiness will be the inconsolable kind, and nothing you do to comfort your baby will work as well as it usually does)
  • Missed naps and/or shorter naps

4 Month Sleep Regression Explained

As we’ve established, all babies go through these changes in their sleep patterns. However, how your baby reacts to these changes will depend on unique factors. Some babies experience a week or two of fussy, interrupted sleep, and then go back to sleeping soundly at night and taking restorative naps. Other babies, however, are thrown all out of whack by the 4 month sleep regression, and they go through weeks and weeks (sometimes even months) of lots of night wakings and missed naps. These babies (and their poor parents!) are hit hard by the 4 month sleep regression, and exhibit a lot of the symptoms mentioned above.

So, if the 4 month sleep regression truly is a bad sleep regression for your baby – how can you cope? Well, we generally advise parents to get to the root of why the 4 month sleep regression is causing such disruptions. Usually, negative sleep associations are to blame – babies who have become accustomed to being rocked or fed or held to sleep continue to need their sleep associations, only now that their sleep patterns have changed, they need them all night long. Of course, mom and dad can’t sustain all that rocking and holding in the middle of the night, and so soon, the whole family is exhausted and overwhelmed. That’s usually when we hear from parents asking for a Personalized Sleep Plan™.

In general, I’d recommend waiting a few weeks, to see if your 4 month old baby’s sleep improves. If it doesn’t, then it may be time to make changes, and to work on weaning your 4 month old from his sleep associations. You might also want to work on establishing a gentle 4 month old baby schedule. I would urge you not to wait indefinitely, though – I talk to parents of 8 month old and even 20 month olds who are still waiting for their “baby” to grow out of their sleep problems.

For more tips on how to cope with and solve your baby’s 4 month sleep regression problems, you can read our other 4 month sleep regression article: The 4 Month Sleep Regression: What It Is and How To Fix It.

4 Month Sleep Regression Help

CaseStudyThumbnailWant more information about how to help your 4 month old sleep well? Check out our detailed case study about Nadia, Brad, and their 4 month old, Abigail.

Read how they helped Abigail learn to sleep longer stretches at night and take better naps – and how they helped to change those sleep associations that were keeping her awake! Just join our Members Area, and access the case study instantly. And that’s not all – our Members Area is packed with additional premium content and resources: e-Books, assessments, more case studies, peer support, and more. It actually costs less to join than buying products separately! And best of all, members receive 20% of all consultation services – that savings alone can actually pay for the cost of the membership!

The 4 month sleep regression means big (and permanent) changes to sleep, but we can help you tackle them. We have helped thousands of families around the world with their babies’ nap trouble, and we can help you, too! Take a look at our consultation packages, and see which one looks like a good fit for you.

Click here to see all our personalized consultation packages.

Once you purchase, you will immediately receive access to the Helpdesk, and you can set up your account, fill out your Family Sleep History form, submit it to a consultant, and get started on the journey to better sleep!

Want more information about how personalized help works? Check out our FAQ page here, and get answers. You can also take a tour of the Helpdesk.

bss_ebook_freeguide_leftWant FREE sleep help that you can put to use right away? Download a copy of our free guide, 5 Ways To Help Your Child Sleep Through The Night! The guide is available to download instantly, which means you can start using the techniques in it as early as tonight. So download now, and learn why your baby is waking at night – and what you can do about it.
Click here to learn more about how to get your free guide.

A better night’s sleep could be just a few clicks away. So don’t wait – download now, and start your journey to better sleep tonight!

Need Baby and Toddler Sleep Help? We Have the Resources You Need!

bss_ebook_3stepsystem_leftFor those persistent nighttime struggles, check out The 3 Step System to Help Your Baby Sleep. Using the same unique approach and practical tools for success, this e-book helps you and your baby sleep through the night.

bss_email_featprod_memberspic-CROPPEDOr, join our Members Area packed with exclusive content and resources: e-Books, assessments, detailed case studies, expert advice, peer support, and more. It actually costs less to join than buying products separately! As a member, you’ll also enjoy a weekly chat with an expert sleep consultant. And the best part – members receive 20% off all sleep consultation services!

Can’t decide which product or service is right for you? Visit our Getting Started Page for help.


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  1. Sandra says

    It’s 530am & I’ve been struggling to get my 4 month old back to sleep for the last hour & half. He’s has scheduled feeding times during the day but not overnight & is exclusively breastfed. By 2 months old, he was able to sleep 5 to 6 hours before getting 1 overnight feeding around 3am & would go back to sleep. Shortly after 3 months, his sleep pattern changed where he would wake up consistently around 1am, 3am & 6am but would only be fed at 3am. At both 1am & 6am I was able to use a pacifier to get him back to sleep in about 5 minutes. In this past week, his overnight pattern is still the same but the biggest difference is now he won’t fall back asleep even with the pacifier. Sometimes I let him cry for 5 min before burping him & giving him some water while still in his crib. Interestingly while he’s sitting up he doesn’t cry but the second I lie him back down he cries. Though I can calm him down with his pacifier & favorite toy to the point where he almost asleep, he seems to wake up 5 minutes later making it a viscious cycle. I feel horrible in that I have to tell my other half not to pick him up to soothe him to sleep or bring him to our bed, as I know it will only start a bad habit that I will need to break. Help! I’m not sure if the issue is I’m letting him fall asleep for the night while breastfeeding.

  2. says

    @Ivana Thanks for commenting! I’m so glad you found what worked for you, but I do want you to consider that what worked for you does not work for everyone. It’s great you were able to successfully co-sleep, but for some of us, it just doesn’t work out that well. I was hyper-sensitive I’d roll on top of him or cover him with a blanket or my husband would roll on him, etc. It was not the best sleep, yet better than getting up every 2 hours. However, long-term, it just wasn’t a solution for us. I respect you disagree that pacifiers or breastfeeding all night (human pacifier) are not sleep associations and it’s great that yours gave it up with no problems at one year, but, again, that is not always the case and some wake for a pacifier replacement ALL night. You, personally, may be able to function on waking every hour (though it doesn’t sound like that happened to you) but others can’t function or become ill more frequently, etc. Again, you might want to keep in mind that what you live day-to-day is not what others live day-to-day and try not to judge others for the decisions they need to make for their own families. Thanks again for sharing what worked for you!


  1. […] 6 Jun Just when I thought I had Nat on a sleep routine and consistent schedule…::pop:: Yes, that is the sound of my happy little bubble being burst. Up until a month ago I was in heaven. Nat was going to sleep at 8:00pm, staying asleep at least 8 hours, waking up once to eat, and then sleeping another 3-4 hours. Getting the little one to drift off to sleep had become a snap as well. Bathtime would start off our sleep routine about and hour and a half before bedtime. After that we play a little bit with dad, maybe read a picture book, and then I would give her one last feeding. Usually all of this would trigger her to relax and I could put her down in the crib drowsy but not asleep. Within ten minutes she’d be sound asleep. As I said, that happy little scenario is gone. For now at least. Getting her to drift off to sleep takes forever, sometimes she’ll wake just 2 hours after being put down. You get the idea, it’s like having a newborn again! Natalia is close to 5 months now, and I know I’m not alone in my sleep dilemma. It’s called 4 month sleep regression. Is it true? I don’t know, but it does seem to make sense. Basically this period in a baby’s development is a time of rapid growth, especially mental. Some experts reason that babies at this age are fast learning and “mastering” new skills. In my browsing for more info on the subject I found that it is believed that sleep is disrupted (or in my case hard to obtain)  because baby’s brain is racing and focusing on getting a certain skill down. Such a skill may be grabbing objects, mastering holding that heavy head up, pushing up when on her tummy, or my little one’s new fav – pulling herself up from sitting to standing. I guess it’s something that could be compared to an adult having trouble getting to sleep or tossing and turning because they’re worried about a deadline the next day. So I’m hoping we get back to our previous sleep schedule soon. Like I said, I feel like I have a newborn again. A very crabby one. Natalia’s new communication skill is grunting to show her displeasure. What’s a mom to do!?  Just know if you too are having sleep problems with your 4 month old, you’re soooo not alone! Here’s a website I found very helpful in understanding what is potentially going on with the little monster – The Baby Sleep Site  […]

  2. […] happens at around 4 months. If you want to read more about the 4 month sleep regression, check out this website. If you register on the website, you even get a free, 18 page sleep […]