Baby Sleep Science Guide: Overcoming The Four-Month Sleep Regression

by Erin Flynn-Evans, Meg Casano

Healthy newborns follow a comfortable pattern. They're up two or three times a night for food and comfort, but you expect these nocturnal disturbances with a new baby.

But at three or four months of age, everything changes. Your baby now wakes at all hours of the night, and exhaustion and frustration become the norm.

The good news is you haven't done anything wrong. Your baby's new sleep pattern (or lack thereof) is a biological response known as the four-month regression.

Infant sleep experts Meg Casano, BSN, MA, and Erin Flynn-Evans, PhD, MPH, provide the knowledge and strategies you need to get through the four-month regression and reestablish restful sleep patterns. Unlike many misleading and uninformed sleep "experts," Flynn-Evans and Casano base their advice on sound scientific principles so that you can act with confidence.

You'll discover how to spot early signs of the four-month regression, how to prevent it if possible, and how to resolve the issue if not. Doing so provides you with realistic expectations of your child's nighttime sleeping patterns and helps you guide your baby back to a healthy, restful nighttime routine.

Genres: Parenting

72 pages, Paperback

Published August 8, 2016

Reviews

[RLV · Rating 4 out of 5]

UPDATE and another read 😅

I sincerely don’t remember how well or not the intervention worked the first time around. But it turned out my child suffers from childhood insomnia (which she has since she was a baby… just thought it was normal messy baby sleep back then 😅). She’s also ND and has been diagnosed with a genetic disease that does play a role in her sleep issues. So there.

Anyway. I read this book again seeing as I now have another 6mo baby who’s not sleeping as well as I would like. 🙈 Turns out I inadvertently created a sleep association between sleep and feeding 👍🏻 Hence our current nightmare.

Giving a try to the baby led intervention this time around. Just as I was the first time I’m super motivated and hope it works. Baby is sometimes cooperative, sometimes not so far. I’ll update on a few weeks 😏

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My baby is 6 months old, so technically past the 4 month sleep regression but i thought i could still benefit from this book, because I have a reaaaally crappy sleeper. She’s just now starting to consolidate some naps but she has them all wrong, ha! The 3rd nap should be the shortest, yet it’s her longest (she takes two 30-something min naps in the morning/afternoon, then the last one before bedtime lasts over 2, sometimes 3 hrs). And of course I don’t want to wake her up too soon because by then she needs it something bad. Meh.

I liked this book. I’m going to try one of the sleep interventions mentioned in it (the one that gives you results the fastest because I’m too sleep-deprived to deal with another month of hourly wakings at night). I’ll edit my review once I’ve given it a week.

I’m so motivated I hope it works! Then again I’m always kinda motivated at 8pm. It’s staying motivated at midnight... and at 1 am... and 2 am... and 3 am... and again at 4 am that’s the issue........oh well, we’ll see how it goes.

[Phaedon · Rating 4 out of 5]

It's a funny thing, paying $10 for a 50 page Kindle Book. I won't lie - it made me hesitate to buy this, but I did it in the end and I'm happy I did. The reality is, we should want to pay MORE for a shorter book, particularly when we're talking about a practical guide on how to get your baby to sleep. So many baby books are stuffed with fluff, and what sleep deprived parent has time to weigh through all that? Still, I also fall victim to the idea that I should get more pages for more money. I'm glad I overcame it this time and I'd encourage all parents in the midst of the dreaded 4 month sleep regression to do the same.

This book is no nonsense. It's easy to read, quite practical in tone and presents a few actionable plans to overcome the sleep regression. It tells you what order to try things in, why they make sense, and how long to expect before you see the benefits. I couldn't ask for much more, other than actual results, but I've only just read the book, and I will find out what those results might look like very soon. In the meantime, I would definitely already recommend this book.

[Shelley · Rating 4 out of 5]

I've been a huge fan of the Baby Sleep Science blog and Erin Flynn-Evans since sleep training my first child in 2022. The blog is the only baby/toddler sleep blog I found (other than Dr. Canapari's) that is scientifically sound and pragmatic enough for every day use. We consulted Erin when my son's sleep training was going horribly (he was 4-months-old at the time): Erin correctly diagnosed him with crib aversion from circadian rhythm misalignment and taught us how to reverse it. He's enjoyed wonderful sleep since then--and we've enjoyed our lives as a result.

I bought this book this time before sleep training our second. I had high expectations and this book came very slightly short, hence the 4 stars.

What I liked:
-very pithy and good explanations of the science and sleep association
-one of the only places where you will find the warning that sleep training this early does NOT solve all night wakings, especially those in the second half of the night -- we floundered over this big time the first time around, and it was a terrible blow to my mental health that even after letting my poor baby cry it out we still had many night wakings; this book sets the expectation wonderfully
-multiple approaches including some very gentle, interactive ones; they didn't work (see later) but I can see them working if I were more systematic

What could've been better:
-more discussion on crib aversion: this was a huge struggle for us the first time and for many sleep training parents, so a discussion on what it is, what it looks like, how to prevent it, and how to reverse it would be huge
-a disclaimer that the check-in method (intervention 2b) may not work on some babies: my daughter was PISSED OFF at the check-ins, especially at the frequencies she suggested; good thing I realized what was going on and really spaced out the check-ins (to basically cry it out), and she did much better with that

So all in all I think this is an excellent resource for younger babies in the 4-6 months age range. I'd recommend it to parents thinking of sleep training, just with the two caveats above in mind.

[Andy Hoong · Rating 4 out of 5]

very detailed and helpful illustration but only good for four months baby

the books offeres very detailed info about four months regression and explains a lot about it but it is only for four months baby

[Tia · Rating 5 out of 5]

This is a quick read, for sleep-deprived parents who have little time to read anything anyway. The book succinctly describes the scientific basis and the gets to the meat: it describes a list of actions you can take to train your baby, based on how gentle you want the training to be.

[Sarah Mason · Rating 5 out of 5]

Quick read and straight to the point

Love it. This is pretty much all the books I have read on development of sleep skills in one place. From the gentle approach to slightly more quick and fast

[Eleanor · Rating 4 out of 5]

Good concise overview and options with clear directions. Look somewhere else if you want more of the why behind the directions.

[Rebecca Saldarini · Rating 5 out of 5]

Easy fast read with practical guidance

Easy to follow and understand why this crazy regression happens. Can be read in an hour and is worth a re-read.

[Cari · Rating 5 out of 5]

Great Advice

Solid, easy to understand advice. A few small tweaks after reading this and my little girl is already sleeping better.

[Kate]

This was a succinct guide to the science of baby sleep. It’s definitely worth a read if you’re lost in the sleep training wars and want some perspective.

[Laura · Rating 4 out of 5]

Useless for our situation but others might find it helpful

[Courtney · Rating 4 out of 5]

I read a little ahead of schedule, may revisit in a month or two

[Jo · Rating 4 out of 5]

4.25 ⭐️s. The first third was especially interesting.

[Sarah · Rating 5 out of 5]

I've read a lot of baby sleep books, but this little book is definitely one of my favorites. The authors don't waste time with a lot of filler--perfect for tired parents who just want to understand what's going on with their child's sleep. There is a clear explanation of the science behind what happens to a baby's sleep at four months of age. The authors then give a few different strategies for how to help your baby sleep better, grounded in evidence-based research.

For parents who are weary of sleep explanations like, "It must be a growth spurt." "The Wonder Weeks says we're in a stormy period." "Try essential oils." or the ever-helpful, "Is he teething?," this book is a breath of fresh air.

[Stacy · Rating 5 out of 5]

Best Sleep Book Ever!

Wow, this book is so refreshing in the fact that it outlines the science behind the 4 month sleep regression. It was fascinating and I have a much better understanding of why my little one is doing the things she's doing and how to fix them. I also love that they don't put a ton of filler in this book. It deals with the facts and gives you the tools to deal with the issues. This is the holy grail of sleep help books and I can't thank the authors enough for writing it!