What Are the Wonder Weeks for Babies?

Find out what the wonder weeks are and get a better understanding of what sleep regressions are all about.
What Are the Wonder Weeks for Babies?
Samanta Ruiz

Written and verified by the teacher Samanta Ruiz.

Last update: 27 January, 2023

Crying, fussiness, interrupted sleep – what’s wrong with my little one? Learn what the wonder weeks are for babies and understand why, many times, you feel that certain things are changing.

For decades, there’s been talk about babies’ sleep regressions and what they mean. In terms of science, the most widespread study is that of anthropologist Hetty van de Rijt and psychologist Frans Plooij, published in 1992. They found that children make certain mental leaps in their development during the first 20 months of life and that these periods can be predicted.

“These difficult periods were mainly characterized by an increase in crying and a decrease in independence and amount of sleep.”

-Hetty van de Rijt, Frans Plooij-

The research of these scientists was turned into a book entitled Wonder Weeks.

Wonder Weeks: When are they and how to recognize them?

As a mom, you know that you have a special connection with your child. If you notice certain changes, that they’re more cranky than usual or that their sleep schedule has been altered, they may be going through one of the so-called Wonder Weeks for babies. During these days, your little one’s brain is preparing for a change. By the time each stage is over, your child will have calmed down and incorporated new learning.

The timing of these leaps has been standardized and, although the weeks may vary (a little more or a little less), the sequence should always be the same.

Week 5 – Leap 1

The baby’s in the process of adapting to their sensations in the new environment. Consequently, they stay awake for more hours in order to recognize their world. During week 5, and often in the last hours of the day, you’ll notice that your baby’s restless and you find it difficult to put them to sleep.

Week 8 – Leap 2

On these days, the baby begins to recognize patterns. For example, they find that they can repeat movements with their hands and also sounds, so they do it over and over again. This discovery makes them restless and probably makes it difficult for them to fall asleep. Therefore, make sure that they’re comfortable and that their room is quiet.

A baby making sounds while lying on his mother's lap.
When your baby discovers that they can repeat movements and sounds, they feel restless and repeat these actions. This makes it harder for them to fall asleep.

Week 12 – Leap 3

The baby can distinguish different tones of voice, and their movements are more coordinated and smooth. Recognizing the world makes them a little nervous. For this reason, they’re more active and begin to change their sleep routine gradually.

Week 19 – Leap 4

They recognize sequences and the causes and consequences of certain simple actions. It’s ideal to take advantage of this new ability in order to create recognizable events, for example, in order to organize an effective sleep routine.

Week 26 – Leap 5

The baby expands its spatial world and understanding of distances. For this reason, they display anxiety when you move away from them. In addition, they’re becoming more and more mobile and are probably already starting to crawl and roll on their own. The latter can lead to interrupted sleep and the subsequent discomfort of not being able to fall back asleep quickly.

Week 37 – Leap 6

During this magical week, your baby begins to differentiate and understand that certain things are different from others. Specialists say they’re able to distinguish categories. Already fully mobile, sleep’s interrupted more than usual by their own movements.

Week 46 – Leap 7

Your baby recognizes simple sequences such as waking up, getting dressed, and eating breakfast. Babies don’t like uncertainty, they like to know what comes next, so they feel very comfortable when they do. They may want to give up some naps and thus alter their sleep routine.

A baby sitting up and smiling while holding a teddy bear.
In week 55, the baby starts to make choices according to their preferences. For example, which toy they like the most.

Week 55 – Jump 8

After one year of life, your baby begins to have preferences and to choose, for example, if they like one toy or another. As they realize they can make choices for themselves, they try to give up some of their naps or stretch their bedtime.

Week 64 – Jump 9

They already know what a sequence is and now begin to understand what a consequence is. They then apply this to achieve their goals. If I do this, this happens. The anxiety of this discovery may upset them and have consequences in their sleep. This is the time to begin setting limits.

Week 75 – Jump 10

Your child’s capable of understanding that different situations are resolved in different ways. For example, things at home and at daycare aren’t done in the same way. In addition, they may change their behavior and adapt to each system or throw tantrums to show that they’re not happy with it. Also, they’re likely to want to alter their sleep times and be unhappy when you want to put them to bed.

Understand what the wonder weeks are for babies to support your child

The main change that all the wonder weeks involve is the evolution of perception. The more they perceive the world, the more curious and anxious babies become, making it harder for them to fall asleep and maintain a sleep routine. You can help them by making their sleeping place comfortable and quiet. The idea is to create a calm environment for your little one to relax.

Although the issue of sleep regression in babies is controversial, we can draw a parallel. For example, think about yourself and how you get restless when you have or discover something new. How do you sleep that day? Well, it’s the same with babies! They need your support to calm down and get a good night’s rest to start the next day.

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