Updated for 2024

Unless you have been living under a rock for the last few years, you will no doubt have heard of the wonder weeks book or the wonder weeks app.

The authors of this book (Wonder Weeks) compared observational studies of infant chimps to the hierarchical perceptual control theory developed by William T Powers, did further human observations and wrote the book The Wonder Weeks.
 
Wonder weeks refer to leaps in mental development and are hypothesised to be linked to grumpy periods or regressions.
 
In total, there are 10 developmental leaps that occur in the first 20 months of a baby's life, and according to the authors of Wonder Weeks, each leap may be preceded by a period of fussiness, grumpiness, or clinginess in the baby's mood and temperament.

 
Knowing this can be empowering for some people; they are confident their baby is not sick, nothing is wrong, and they are simply developing.

For parents who find this knowledge overwhelming, it may be best to delete the app, return the book to the library, and simply enjoy your baby!

Your baby is a baby, not a robot, so they will have a fussy, grumpy period, but you are a fantastic parent and will no doubt respond accordingly.
 
We have found the sooner our clients establish healthy sleep habits and predictable routines, the easier they navigate fussy stages and minimise any periods of unhappiness.

This is due to parents being able to confidently read cues within the context of what they know their baby needs or does not need.
 
If you have a regular routine and your baby is able to self-soothe without any difficulty, then during a "stormy period week x", you can easily identify whether your baby is just feeling a bit grumpy or if they are in need of a nap or feed. On the other hand, if your baby seems to be getting restless, it could be an indication that they need a change of scenery.

You won't be second-guessing your nap routine or how much sleep your baby needs. Having this predictability helps you meet your baby's changing needs before crying and fussing.
 
Many clients express their concerns about the impact of wonder weeks on their baby's sleep. Although we understand that during these developmental leaps, new brain synapses are formed, skills are mastered, and the brain is engaged in a lot of activity, we also know that sleep is crucial for transferring these skills from short-term to long-term memory. However, it is possible for your baby to continue sleeping well during these wonder week leaps, particularly once they have established predictable sleep patterns.
 
The only notes I can find in the Wonder Week's book on sleep say virtually the same things for every leap.

• Less sleep
• Nap strikes
• Early wakes
• Delayed onset of sleep

Now, while this certainly covers pretty much any sleep blip, as a parent reading Wonder Week's book, I felt this wasn’t a book to help me with sleep but just to understand development and fun ways to encourage this development.

Below you will find a guide on what happens to your baby’s sleep during these wonder week leap periodsand some helpful tips.

So do your mum's friends a solid and share this with them if they’ve ever mentioned the Wonder Week's app to you.

Wonder Week Leap 1

5 week old (1 month) 
 
New-borns are born with a level of melatonin from their mothers, this makes a lot of new-borns relatively sleepy in those first few weeks.

As it wears off, your baby will “wake up” to the world, and this can start to present issues with settling if you previously managed to just pop the baby down and they slept thanks to the flood of maternal melatonin.

Try hands-on settling techniques and experiment with different styles to see what works best for your baby.

Wonder Week Leap 2 

8 weeks old (2 months)
 
Crying peaks in newborns between 6-8 weeks of age, so this can be a tricky time for many families. Cluster feeding is on its way out, and your baby might be craving an earlier bedtime routine and more sleep pre-midnight if they were previously a cluster feeder.

By 8 weeks, newborns are happy to stay awake for up to 1.5 hours between naps, and sometimes parents don’t realise how quickly their baby's awake window increases and may be trying to settle an under-tired baby.

Ensure your newborn is making good weight gains each week, as a hungry baby will be a fussy baby who doesn’t sleep well.

Wonder Week Leap 3 

12 weeks old (3 months)
 
Your baby’s circadian rhythm is pretty much fully formed; they know the difference between night and day, and this is a great age to work on consistent naps and establish a nap routine and pre-sleep ritual to encourage independent settling when your baby is ready.

Many babies begin to outgrow being rocked and patted to sleep, which can gradually frustrate and not settle your baby. Some babies begin to roll from tummy to back and may fight being swaddled.

Try transitioning to a one-arm-out wrap and a sleeping bag. Your baby is likely experiencing waking after 45 minutes as their sleep cycles are very obvious by this age, and you’ll need to start working on teaching your baby to go down awake to help with this. Try our mini guide to learn EXACTLY how to put your baby down awake, from newborn to 12 months!

Wonder Week Leap 4

19 weeks old (4 months)
 
Welcome to the 4 month sleep regression month.

If you hadn’t noticed sleep cycles of 45 minutes previously, you may well this month. Your baby is entering the period where they can begin to use their positive sleep associations to start to settle themselves to sleep and back to sleep. This can be an essential skill to work on if you start to notice 2 hourly wake-ups at night. Re-settling when not hungry will help prevent reverse cycling, and encourage natural consolidation of night sleep.

Wonder Week Leap 5

26 weeks old  (6-7 months)
 
It's the biggest month for sleep changes so far!

Starting solids affects the gut and how your baby feels with new bi-products of food digestion.

Rolling both ways starts, and your baby might prefer to roll when it’s sleep time. this can result in delayed settling, more crying when settling, and both mum and baby feeling frustrated.

You definitely need to un-swaddle if you haven’t yet, and this newfound freedom can be a tricky transition. Dream feeds can disturb your baby's most deep stage of sleep and should be dropped in this age bracket, too.

All these new skills mean new brain synapses forming and can result in unsettled sleep periods, but be confident this is the ideal age to work on self-soothing and encourage a long midday nap and 6-8 hours sleep at night.

Wonder Week Leap 6 

37 weeks old (9-10 months)
 
By 8 months, your baby has object permanence; they understand when you leave the room, you still exist. This can lead to separation anxiety, which may disturb bedtime settling. Try pop-ins or sitting quietly while your baby settles to sleep.

Crawling is well established, and this is a big movement for your baby to grasp. Babies love to crawl when they're meant to be sleeping!

When your baby crawls, they have to change their eye focus from the ground to the horizon, and this helps build new brain synapses. Combined with the crisscross body movement of arms vs legs means your babies brain has a lot to process sleep time! 

Don’t try to force your baby to lie down in their cot if they are moving and cruising around. It’s normal for all babies to learn to lie down when they are tired to sleep. Your baby will be well-established on 3 meals a day, and you can likely drop all-night feeds if you haven’t already.

Wonder Week Leap 7 

46 weeks old (11-12 months)
 
The 12 month sleep regression is the biggest regression of them all in my opinion, but the one which requires us to “do” the least. Your baby might fight their morning nap, but most babies still need this nap despite refusing it for a couple of weeks.

Continue to offer the nap, and limit it to 15 minutes if the lunch nap starts to shorten. Your baby is learning to pull up to stand, walk, and say words. They understand consistent routines for set activities, and you can use this to your advantage by having a nice relaxing pre-sleep ritual before your naps and bedtime.
 

Wonder Week Leap 8

55 weeks old (13-14 months)
 
By 15-18 months, your baby will drop to one nap; the month preceding this can be a bit messy, with your baby sometimes taking their morning nap and sometimes skipping it.

Your baby will be very physical and physically tired. They still need 11-12 hours of sleep at night but may start to show you some pushback as they test their independence out on you. Have consistent routines and allow your mini toddler plenty of time to wind down to prepare to sleep at night. Stories and quiet time.
 

Wonder Week Leap 9

64 weeks old (16 months)
 
If you have great sleep habits established you should make it though these months relatively unscathed…..you may however need to start saying “no” as your toddler starts to test bed time boundaries.

Remember that crying out for milk at night is a boundary, and if you have previously night weaned, be consistent with your boundary and your toddler will quickly re-consolidate their night sleep.

Conversely, early waking toddlers are also testing the boundary of calling out at 5am and looking to see what the cause-and-effect relationship is here. Do they get up and get to play? Or are they expected to go back to sleep?

Wonder Week Leap 10

75 weeks old (18 months)
 
Many parents are starting to be comfortable with discipline in the day at this age, but struggle to view tantrums around sleep to be the same as tantrums around getting in a car seat or sitting in a highchair to eat. Be consistent in your approach both day and night.

Your toddler will definitely be on one nap by this age and will begin to gradually over the next 12 months shorten his/her nap, and start to need slightly less sleep at night.

Separation anxiety can rare up this age, build confidence in your toddler by popping back to check on them at bedtime, consider leaving the door open a little, and avoid bedtime stalling tactics with a good bedtime routine.

This is a typical age for a new baby to emerge on the scene, and parents struggle with the juggle of a newborn and a toddler refusing bedtime. Avoid this by establishing those boundaries and routines before the new baby arrives.
 
77 weeks old  (20 months)
 
You’ve made it through the busy 20 months.

There is, however, a 2 year sleep regression which is commonly associated with separation anxiety. Introduce a night light, try leaving your toddler's door open a little at bedtime, and if need be, sit with them while they fall asleep, but try to avoid climbing into bed with them unless you are happy to continue to do this long-term.

Are you overwhelmed or intrigued to see these developments emerge in your baby?

Remember, all babies experience these changes differently, and there is no better time to work on good sleep than the time when you are ready.

Don’t be put off thinking there is a new wonder week leap coming and sleep will fall apart, or sleep training will be impossible.

All of our 100,000 clients have chosen to improve their baby's sleep when the time was right for them and their families despite any impending wonder week leaps, and as you can see your baby will be growing, changing and developing so much in the first two years, it would be almost impossible to find an “ideal” window in that time.
 
Do you have the Wonder Weeks app or book?

How have you found it? Comment below and share your story with our community.