What are “The Wonder Weeks,” and how to the affect your baby’s sleep? Keep reading to find out!
Picture this: Your little one was born about 4 weeks ago, and you’ve finally found your rhythm.
Whew! Everyone told you newborn parenting would be exhausting. And sure, you’re tired, but it’s not too bad!
Your baby sleeps most of the day and night; they wake only to eat and for short spurts of alertness before dozing back off.
But around week 5, things start to change. Your baby is more alert and stays awake for extended periods. They’re fussy and harder to get to sleep.
Mom, welcome to Wonder Week 1–the first of your baby’s developmental leaps.
As a pediatric sleep consultant and mom of two, I always encourage my clients to have a copy of “The Wonder Weeks” on hand so they can learn about their baby’s developmental leaps.
But what are The Wonder Weeks, and how do they affect your baby’s sleep patterns?
Keep reading to find out!

What Are The Wonder Weeks?
“The Wonder Weeks” is a best-selling book by Hetty van de Rijt and Frans X. Plooij. It outlines the 10 developmental leaps, or Wonder Weeks, a baby experiences in their first 20 months.
For decades, parents have used this book as a guide through their baby’s first year+ of life, and it’s been a lifesaver for many confused moms and dads.
I love and recommend this book for 3 reasons:
- It helps new parents understand what’s happening in their little one’s development.
- It can sometimes* explain unusual or “off” behavior
- It helps new parents feel more confident and better prepared for what’s ahead.
If your baby is suddenly fussy, fights sleep, and seems “off,” there’s a good chance a developmental leap is to blame!
*Contact your pediatrician if you’re worried about your baby’s behavior and feel it could be health-related. Trust your gut, Mom!
The Wonder Weeks and Sleep
Before we get into the nitty-gritty, know that developmental leaps are not precise. Each child is different, which means they develop at different rates and with varying symptoms.
For example, some babies might not be affected much by their developmental leaps, while others might check off every sign in the book.
In other words, these developmental leaps don’t always happen by the numbers, but they do happen.
And they almost always impact sleep. During most leaps, you can expect your little one to:
- Resist sleep,
- Wake more frequently at night and/or
- Wake earlier
Most developmental leaps last from 3 days to 2 weeks, but some can last longer.
Developmental Leaps Are Good!
While frustrating, you want your child to experience these developmental leaps. In fact, if you notice your child isn’t “leaping” or is significantly behind, you might want to reach out to your pediatrician.
Why? Because they are usually associated with new skills.
For example, around Wonder Week 19 (Leap 4), your baby might start to sit up and even initiate crawling.
Developmental Leaps are signs that your baby is healthy and growing properly!
Related: 10 Science-Based Sleep Tips for Tired Moms
Wonder Weeks Tips
First, when you know when each Wonder Week occurs and what to expect during the developmental leaps, you will feel more confident and at peace. I highly recommend purchasing the book before your little one arrives.
It will also help you plan vacations, road trips, and visits with family. For example, avoid a long vacation if you know a developmental leap is coming up.
Secondly, try to be consistent during these leaps. Stick to your routines (as much as possible) and avoid picking up bad habits, such as rocking, holding, or feeding to sleep, as these are very difficult to drop once started.
Wrapping Up
While the Wonder Weeks can be trying, they’re also WONDERFUL.
A developmental leap means your little one is progressing and growing.
Remember:
- The Wonder Weeks mark the 10 developmental leaps from birth to 20 months.
- Developmental leaps typically coincide with new skills, such as sitting up and crawling.
- Sleeplessness, resistance to sleep, fussiness, and early wakeups might accompany a developmental leap.
- During leaps, it’s essential to stay as consistent as possible.
If your little one still struggles with sleep after a leap, please reach out! I’m happy to help you get the sleep you need.
You can also find me on Instagram, where I share sleep tips and tricks.