The Wonder Weeks and Sleep Training

The Wonder Weeks

​Have you ever woken up to the sound of a crying baby and thought to yourself, “That’s it. This week, I’m taking some action. This week, we’re going to start teaching that baby some sleep skills.”


Then, sometime in the early morning, when your third cup of coffee starts to kick in, you find yourself second-guessing the idea. Maybe you feel like things aren’t that bad yet, or you get into the “I knew what I was getting into when I decided to have a baby” mindset, or maybe someone told you that this wasn’t really the right time since your baby was just about to go through a big developmental milestone, and makes a reference to The Wonder Weeks.


For those of you who aren’t familiar with it, The Wonder Weeks is something of a Farmer’s Almanac for babies. The husband-and-wife team of Frans Plloji, a behavioural scientist, and Hetty van de Rijt, an educational psychologist, developed it. 


The concept goes something like this: Starting at five weeks old and continuing through the 20-month mark, babies go through 10 mental development stages or “leaps” as the authors refer to them. According to the book, these leaps take place at very specific points in a baby’s life, starting at five weeks and continuing through the 20-month mark. 
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“Sunny weeks,” during which baby is typically happy and agreeable, are followed by “stormy weeks,” during which baby is fussy and inconsolable due to neurological development, and then comes the “wonder week,” where the new skill or development is mastered, and baby goes back to being “sunny” again.


Many, and I mean many parents, absolutely swear by this book and its popular companion app. (The original book has sold over 2 million copies across 25 languages.) Some people even claim that it tracks their little one’s development to the day as opposed to the week. 


Others will tell you that the science it’s built on is flawed and that what the authors are doing is essentially a form of pediatric astrology, making vague predictions based on norms and averages and reassuring its followers that good things are perpetually just over the horizon.


There are a couple of things to consider for your data-driven types out there. The 1992 study that The Wonder Weeks is founded on used a sample size of just 15 participants and relied almost exclusively on questionnaires filled in by the mothers as opposed to direct observation from the researchers. Dr. Plooij’s counterargument for the small sample size, stating that if you find behaviour in two individuals, “then you already have proof that the phenomenon exists and is not due to luck or chance,” doesn’t do much to shore up his credibility.


In the mid-1990s, Dr. Plooij’s Ph.D. student, Dr. Carolina de Weerth, attempted to replicate the findings from the original study with an even smaller sample size of four babies and failed to reach the same conclusions. Dr. de Weerth claims Plooij pressured her to find correlations supporting his original research. When she refused, he attempted to prevent the publication of her findings. (A claim that Plooij denies.) Plooij’s contract with the University of Groningen wasn’t renewed following the incident, and he subsequently left academia altogether.


Suffice it to say, there’s still controversy and debate over its legitimacy. But hey, that’s nothing new when it comes to the world of parenting. Is anything ever written in stone when it comes to babies?


If parents take comfort in being able to predict when their baby will be cranky, I think that’s just fine. If it helps them through a prolonged period of crying to think, “This is just her developing as she’s supposed to,” then high fives all around. Parents need all the support they can get, and I say take your mental health boosts where you can find them. 


The potential downside I see is that parents might put too much stock in the accuracy of the book or the app and develop some unnecessary concerns if things don’t go according to schedule. If there’s one thing parents don’t need, it’s unrealistic expectations based on inaccurate research, telling them that their little one has failed to hit a developmental milestone on time.


And that brings us to the reason why I wanted to speak on the whole Wonder Weeks subject today in the first place. 
At what point in a baby’s development should you start putting a priority on their sleep?


Should we wait until after some of these milestones have been cleared? 
If so, which ones? What can happen if we get started too early or too late?


So, let me state this unequivocally. Outside of a diagnosable health issue, there is absolutely no “wrong time” to teach your baby to sleep well.
Right before a “sunny week,” right at the tail end of a “stormy week,” or smack dab in the middle of a “wonder week” are all perfect times to get the ball rolling. There are no developmental milestones, specific weeks, or times in a baby’s life that could be considered the wrong time to get them to sleep well.


I’m confident you’ll never find a pediatrician who contradicts me on that statement. It’s not controversial among the scientific community or medical professionals. We’re all in agreement that adequate sleep is essential to the health and well-being of everyone in the family unit and that teaching your baby some independent sleep skills is safe and effective, whether it’s week fifteen or week fifty-five. 


There are situations where I’ll tell parents to hold off for a few nights, say if they’re going on holiday within a week or so. I tend to recommend that they get started on a night when they don’t have to work early the next day, as night one can be a little on the turbulent side. Still, you should never delay your plans to help your baby develop their sleep skills due to some upcoming milestones. Those will keep coming, week after week, and your baby will have a happier time progressing through them if they get the sleep they need.
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