What are The Wonder Weeks, and how do they affect sleep? (Part Two)

‘The Wonder Weeks’ is a book that was written by a husband and wife who completed their studies in Educational Psychology, Physical Anthropology and Behavioural Biology. After spending two years studying the behaviours of chimpanzees in Tanzania, East Africa, they returned to Europe and compiled their data. Analysis determined that there were significant ‘regression’ periods where the infant would cling more to the mother, and this was found to be the case in at least 12 other primate species.

After completing their Ph.D. degrees, the couple went on to observe human mothers and infants and found that they too experienced similar ‘regression’ periods and similar behaviours as a result. At the same time, these infants would make a ‘leap’ in their mental development.

What are The Wonder Weeks?

The Wonder Weeks consist of ten developmental growth spurts (or these ‘regression’ periods, as mentioned above) that a child experiences in their first 82 weeks of life. Although they often coincide with physical growth spurts, they are actually a different phenomenon and are usually marked by a child becoming increasingly clingy, cranky, and crying more often.

Each Wonder Week (or ‘Leap’, as it’s sometimes referred to) can last anywhere from 3 days to [gulp]… 6 weeks! But the good news is that the most intense behaviours usually don’t last for more than 1 to 2 weeks, with some Wonder Weeks not affecting a child at all. I also find that each Wonder Week is fairly accurate based on a child’s due date (not date of birth), give or take a week.

But the big question you’re all wanting me to answer here is…

How do they affect sleep?

You may like to read Part One of this post first. 🙂

Wonder Week 37 – Categories

This Leap begins around 33.5 weeks and ends around 37.5 weeks.

A child this age begins to experiment with things, and is learning that everything can fit into a category. Through experimentation comes even more encouragement to get moving, with some children even beginning to walk now. This too is often a tough leap, as it tends to coincide with the 8/9/10 month sleep regression, along with another physical growth spurt.

The sleep issue during this Leap is often even more new-found mobility. As mentioned above, with new-found mobility, help your child to practice their new skill while awake, in and out of bed, so that they can master their new skill quickly and no longer feel the need to practice it when they should be asleep.


Wonder Week 46 – Sequences

This Leap begins around 41.5 weeks and ends around 46.5 weeks.

A child this age is learning that everything in life has an order. This Leap often coincides with 11/12 month sleep regression – although this one only usually involves naps. Some children will appear as though they’re ‘giving up’ their morning nap, when really they still need it to continue for another few months.

The sleep issue during this Leap is again often a lack of routines. It’s important now more than ever to be consistent and firm with routines, which help a child to feel safe and secure, as they know what’s expected of them and what they can expect from their parent.


Wonder Week 55 – Programs

This Leap begins around 50.5 weeks and ends around 54.5 weeks.

A child this age is building on their knowledge from the previous Leap, and learning that different sequences can achieve the same result.

The sleep issue during this Leap is often separation anxiety and an exertion of independence. Bedtime and naptime can become more of a battle as the child tests the boundaries, and really begins to act on their parent’s emotions. If mum or dad are feeling anxious, a child this age can really feel it and will begin to act on the unsettled emotions that they can sense. It’s always important to feel confident around the sleep context with children, but particularly around this age when children are experiencing a peak in separation anxiety themselves.


Wonder Week 64 – Principles

This Leap begins around 59.5 weeks and ends around 64.5 weeks.

A child this age is learning to use their cause and effect knowledge along with their exertion of independence… and attempt to get what they want! In a nutshell, they realise that their actions have consequences and will often show this around the sleep context.

The sleep issue during this Leap is often not related to sleep, but rather discipline. It’s important now more than ever to establish boundaries around the sleep context and ensure that you are consistent in maintaining those boundaries.


Wonder Week 75 – Systems

This Leap begins around 70.5 weeks and ends around 76.5 weeks.

A child this age is learning that their family is different from other families, childcare is different to home, and the rules with Mum are different to the rules with Dad. This Leap often coincides with the 18 month sleep regression, which can be one of the toughest yet. Tantrums are usually in full force during this Leap, and they can occur at bedtime and naptime!

The sleep issue during this Leap is again often not related to sleep, but rather discipline. Boundaries are one of the highest forms of love, providing a child with a feeling that everything is under control.

For older children who struggle with nightmares, I will often recommend eliminating all television shows that even show a hint of a child who is defiant toward their parent. Why? Because when a child watches this behaviour, it makes them anxious, knowing that boundaries are being tested, and things may not always be under control by the person who (in their mind) should have things under control. This can often result in those anxieties surfacing at night in the form of nightmares!

So for a younger child in this age group, the same idea is relevant, and although it may not yet show in the form of nightmares, it will show in their behaviour in one way or another. Bottom line – set boundaries!


As with all stages in a child’s life, The Wonder Weeks are temporary. If you’re experiencing a tough one, just remember that ‘this too shall pass’! The good news is that a child who has learnt the skills required to sleep well is much less affected by The Wonder Weeks, so if you feel that you need some help, feel free to contact me because I would love to help you!

I’d love to hear your thoughts on the topic!