Developmental milestones & sleep disruptions

As a mom, as well as a sleep consultant who has worked with hundreds of parents of babies and toddlers, I’ve come to the indisputable conclusion that babies, as a rule, are complicated creatures. From the outside, it seems like things should be fairly straightforward - they eat, sleep and poop so if your baby is crying it must be related to one of their vital needs. But as any parent knows, identifying the fact that there is a problem is far, far easier than solving the problem, and as parents, that’s what we want to do.

Now, if you’re the parent of a baby who’s learning to crawl, or who’s teething, or just figured out how to roll over, this may come as the least surprising scientific discovery imaginable, but developmental milestones are likely to cause disruptions in a baby’s sleep.


In a 2015 study published in Monographs of the Society for Research in Child Development, researchers looked at the sleep patterns of babies before they started crawling, while they were learning to crawl, and a few months after learning to crawl. The results stated that, “Along with the overall improvement in sleep consolidation, periods of increased long wake episodes were also manifested; the rise in sleep disruption was temporally linked to crawling onset. The results of the study highlight the dynamic interrelations between domains of development, indicate that emerging motor skills may involve periods of disrupted sleep, and point to the moderating effect of age.”

To simplify that, babies appear to have more nighttime wake-ups around the time that they learn to crawl. (Nighttime wake-ups were monitored by a motion sensor on baby’s ankle and were only counted if baby was moving around for more than five minutes.)

To quote that same study, “In dynamic systems, downward trends in performance and in behavioural control often mark the emergence of new abilities. This pattern has been identified in diverse domains of infant development including manual reaching, vocal production, and language acquisition.” 

Or, in layman’s terms, things tend to get worse before they get better, and when your little one starts learning to talk, you can expect some random blathering sessions in the middle of the night.

Developmental milestones or “leaps” happen throughout childhood. Whether it’s your fourth month old learning to roll, your nine month old learning to pull up to stand or your one year old learning how to walk, they are constantly learning and will have the urge to practice their new skill until they master it. In the morning, in the afternoon, and when they wake up in the middle of the night. This excitement can make it more difficult for a baby to fall asleep for naps and bedtime and for them to get back to sleep in the middle of the night.

I often hear from parents looking for a “solution” when their child is going through one of these leaps, and in trying to get their baby’s sleep back on track, they tend to lose consistency. They’ll move bedtimes around, start rocking or feeding baby back to sleep, change up the bedtime routine, anything they think might help. But the best advice I can give you is to hold steady. 

You’re probably going to have a few frustrating nights where you have to go in and soothe your baby a little more or you’ll have to help get them out of the uncomfortable positions they manage to get themselves into, but like they say, “this too shall pass”. And, unfortunately if you resort to “quick-fixes” like rocking or feeding to get your baby to sleep quickly, it is very likely to end up creating dependencies that will last long past the time your baby has mastered their new skill.

So, what can you do? Offer them some comfort, tell them it’s still bedtime, help them get back into a comfortable and safe position if they’ve gotten themselves pushed up against the side of the crib, or roll them onto their backs if they’ve flipped and are stuck, but make sure to let them get back to sleep on their own. That way, once they’ve got this new skill mastered, they’ll still have the ability to self-soothe when they wake up at night. If your baby is just exploring the crib, or is sitting up and laying back down, there is no need to intervene, just let them do their thing. Lastly, during their awake time, it’s important to give them plenty of time to practice, practice, practice. The more opportunity they get to practice that new exciting skill during the day, the less likely they are to do it at night.

It’s likely to be a bit of a challenge, and it may feel at times like one skill gets mastered just in time for another one to start developing, but hang in there. The whole time this is going on, your baby is also developing the ability to better consolidate nighttime sleep, so stay consistent and you can expect even more of those glorious sleep-filled nights once they are on the other side.