Developmental Milestones & Sleep: The Truth About The Wonder Weeks
“My baby is in Leap 6 and waking frequently, what should I do?”
I get versions of this question every week in my Monday Q&A’s! Developmental milestones and how they can impact sleep is a common concern for parents, and often the ever-popular Wonder Weeks are a big part of this conversation!
What are The Wonder Weeks?
If you’re a parent in 2023 it’s very likely you have heard about “The Wonder Weeks” app, but did you know that this app is originally based on a book? The Wonder Weeks was originally written by a dutch husband-and-wife team, Frans Plooij and Hetty van de Rijt, in 1992. Plooij was a behavioral scientist who studied mother-and-baby interactions in chimpanzees. He, along with Hetty, translated his observations to describe how human babies go through 10 developmental phases, or “ leaps,” that help them build awareness of the world around them. Decades later the popular Wonder Weeks app was born and parents around the world started to follow the 10 “wonder weeks”, and the warnings of changes to their baby’s disposition, behavior and sleep that comes along with them.
For some parents, following the Wonder Weeks app is helpful, having a possible explanation for their baby’s increased fussiness can be reassuring. For others, seeing the leap calendar and anticipating those “stormy periods” can be totally anxiety inducing! One of the biggest concerns that anxious parents have is how their baby’s sleep will be impacted by these leaps. Both the wonder weeks book and app states that: “your child may sleep less well, may resist going to bed, have difficulty falling asleep, and wake up sooner. Some will sleep less well in the day, and others at night, some will simply refuse to sleep” , but is this really true?
Lets look at the research behind the “leaps” themselves.
Most experts agree that the Wonder Weeks “leaps” shouldn’t be treated as gospel, or used to evaluate a baby’s development in any way… because there is NO research to back them up! Interestingly, there is also some controversy surrounding this! One of Plooij’s doctoral students conducted her own research studying human babies to see if she could back up the theory of 10 distinct “leaps” outlined in the Wonder Weeks book. Not only was she unable to do so, but when she went to publish her findings Plooij tried to block her work. This situation was followed by a lot of debate, and eventually Plooij’s firing from his academic position. Yikes!
Now this doesn’t mean the cognitive developments outlined by the Wonder Weeks don’t happen, just that their pattern can look very different for each baby, and the leap itself is not what’s causing changes in development. I also believe that generalizing long periods of fussiness or sleep challenges as part of normal “leaps” can sometimes mask true health or sleep issues. Far too often I see families wait for a long “leap to be over” in the hopes that sleep will improve on its own, when their challenges have little to do with developmental shifts.
This isn’t to say that both cognitive and physical developmental milestones can’t affect sleep, we know they can! But the degree of disruption is largely dependent on how well baby sleeps generally (more on this later), and how we support our baby through each milestone, NOT how long a leap is supposed to last or how “stormy” its supposed to be. Here are some of the major mental and physical developmental milestones that can affect sleep within the first year of life, and some tips on how to navigate them:
1) The Four Month Sleep Regression
Yes! This IS a developmental milestone, and likely the reason for that long “stormy period” of sleep around the time of leap 3/4 as laid out in The Wonder Weeks. This sleep regression gets a bad rap, but it really just marks a developmental progression in the way a baby’s brain organizes sleep. Instead of having two sleep stages (newborn sleep is either active and deep) your baby will now permanently sleep in 4 stage sleep cycles like us adults. These sleep cycles mean that baby is now in light sleep more frequently, which unfortunately means more opportunities for wake ups! For some babies, the four month sleep regression leads to a few rough nights as baby figures out how to connect those sleep cycles, and then they shift back to their normal waking pattern. For other babies, this is a more challenging process! If you are at the point where your little one is not showing signs of improvement after 2 weeks of rough nights, you may want to consider teaching your baby how to initiate sleep independently so they have the skills they need to connect their sleep overnight. If this feels overwhelming, we would love to help- learn more about our sleep support services here.
2) Rolling
I often see this milestone hit while working 1:1 with families to teach independent sleep! Once we drop the swaddle and begin putting baby down awake, rolling is pretty inevitable. It’s a good thing actually, because we want baby to be able to have the freedom to roll back and forth and find their place of comfort. It’s also totally necessary for a baby to practice this new skill, and the crib is a safe place for that to happen! Unfortunately all of this practice can affect sleep if baby feels like they are getting stuck when they only know how to roll the one direction. Here is what I recommend:
Daytime practice! Help baby get all that rolling out of their system by providing lots of practice opportunities. I like to have my families use a blanket under baby to gently help them to roll back and forth- make it fun!
Resist the urge to flip baby over every time they roll in the crib. While we should always place baby on their back to sleep, both the American Academy of Pediatrics, and Heath Canada agree that once a baby can roll onto their tummy themselves, it’s okay to leave them that way. Some babies are upset after rolling onto their tummies, but if we repeatedly flip them back we need to be prepared to do it 165362 times a night. Instead, I recommend focusing on helping baby learn to be comfortable there by soothing them in place rather than flipping them over.
3) Sitting and Standing
Similar to rolling, these physical developmental milestones can impact sleep pretty intensely for some babies who just can’t seem to turn off the skills practice in bed! The very best thing to do if your little one is constantly sitting or pulling themselves up in the crib is to teach them how to get themselves out of these positions! It seems silly, but babies really can feel stuck standing or sitting, and helping them realize they CAN get out of these positions themselves is key to them being able to figure it out in the crib. Use your coffee table and some favorite toys to gently guide baby down from standing, or even practice with them in the crib during awake time! Putting that daytime effort in will start to pay off in 3-5 days for most babies, and will allow you to let them work it out themselves during bedtime or a night wake up.
4) Separation Anxiety
While the Wonder Weeks states that separation anxiety peaks at 29 weeks, this can be SO different for each individual baby. I often see an increase of separation anxiety around the 6-7 month range, and then again sometime around 9-11 months. Separation anxiety is TOTALLY normal, and comes when baby starts to grasp the concept of object permanence (the understanding that when something disappears, it’s not gone forever). Here are some tips to best navigate this when it comes to sleep:
Stick to your normal routines! Don’t begin assisting baby to sleep if that’s not what you typically do.
Make goodnights quick and don’t sneak away- hesitant or drawn out goodbyes are much harder for little ones.
Practice separation during the daytime! Peek-a-boo, or practicing leaving baby’s line of sight briefly can help them learn you are always still close by.
Of course, there are other milestones too! Baby finding their hands, learning to babble and talk, crawling, walking, etc. ALL of these can temporarily impact sleep, but there is no defined pattern or concrete prediction as to when or how. Its also important to remember that our babies are in a continuous state of development, totally on their own timeline. Another important thing to keep in mind when your baby is going through a developmental shift is that sleep needs may be changing as well. As our babies get older it only makes sense they need more awake time! Often I see a baby struggle more with something developmental, like standing in the crib, if they are being put to bed before they were quite ready for sleep. Sometimes just bumping up their wake window slightly is key to helping them overcome their crazy urge to practice those new skills! If you have no clue where to start when it comes to baby scheduling, our Solve Your Sleep Scheduling Guide is definitely the place to start! Download it here.
Babies with independent sleep skills are typically less affected by developmental milestones…
When a baby requires our help to fall asleep at bedtime they likely require that assistance to fall back asleep each time they wake overnight. This can make developmental milestone related wake ups much more challenging! Take rolling for example: if your baby is used to being rocked to sleep and they wake themselves up after rolling over, you’ll rock them back to sleep then place them back down sleeping, only for them to roll again and the process starts over! Babies who have the ability to initiate sleep on their own may still struggle with rolling for a few nights, but they will much more easily figure out how to get themselves comfortable and fall back asleep after rolling. Same story with separation anxiety! How can we NOT sneak away from our little ones if we are placing them down fully asleep? When they wake, they will PANIC because we are gone, and the process repeats itself….all night long.
Trying to determine if your current sleep challenges are due to a developmental milestone can sometimes be tricky! A good rule of thumb is that most developmental milestones impact sleep for only a short period, 1-2 weeks at most. If your little ones wonky sleep seems to be lasting longer than 2 weeks, it’s likely something else is at play, possibly a scheduling issue or a lack of independent sleep skills. If you need some help figuring out what’s causing your little one’s sleep trouble, let’s book a free sleep evaluation call! Your baby’s sleep doesn’t have to be a disaster for big long stormy periods, we can teach them the skills they need to handle all of the developmental shifts that will come their way!
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