Newborn to Toddler; Mental Leaps, Growth, and Sleep

During your baby’s first two years, they make incredible cognitive leaps and undergo some unexpected wallet emptying growth spurts. Thanks to science, we now know that these leaps occur at around 4 months, 9 months, 13 months, 18 months and 24 months (see

From birth to two years old, your baby moves from barely recognizing you to a toddler who walks, talks and can feed themselves among numerous other skills. While your child is learning these skills, you will notice that their sleep pattern changes. If your child starts to sleep poorly and becomes grumpy and clingy during the day, they are probably going through a mental leap.

A note on sleep regression

Baby is not regressing but rather progressing through a real, measurable and significant development milestone. Development milestones are not just physical but also emotional and neurological.

Babies process information in their sleep. This means they will babble, try to crawl, move their feet and perform all the new skills they are learning in their sleep. They probably rolled over in their dreams and did it in reality too which woke them up.

Their busy brain is not letting their body get as much sleep as they would like which is why they are fussy and clingy in between and during these developmental milestones.

As they master each milestone, their sleep pattern will return to normal, until the next milestone that is.

Use the chart here to calculate your baby’s exact age in weeks and months and read on to find out what’s going on with them.

Week 1 to Week 4

The first three months of your baby’s life are considered the fourth trimester. Your baby should be fed on demand and should be held as much as possible.

What’s normal when it comes to feeding you ask? Depends on your child, there are as many kinds of normal as there are babies. During this first month, your baby will undergo growth spurts at:

  • 7 to 10 days
  • 2 to 3 weeks
  • 4 to 6 weeks

Baby, Growth, Parenting

Wonder Week 5; Mental Leap 1

Changing sensations

You have watched your baby grow rapidly over the past 4 weeks, and you’re starting to feel confident that you know all his ways. Your child is just now starting to make sense of what has been happening and is about to take their first development leap.

Your baby is starting to perceive sensations other than hunger and discomfort.

As you can imagine, your baby is experiencing everything for the first time, everything! Not just mentally but also physical development and that of his internal organs.

6 to 7 weeks

Between 4 to 6 weeks of age, your baby will be going through a growth spurt.

Baby, Growth, Parenting

Wonder Week 8, Mental Leap 2


At about 8 weeks of age, your baby will begin to experience the world in a new way. They will now be able to recognize patterns not only in the world around them but also in their body. You will notice your baby is fascinated with shadows or tries to study the details of everything.

They may also spend hours playing with their hands and feet and trying to control them or trying to listen to themselves by making short bursts of sound.

Any of the above signs signals a mental change happening in your baby. Adjusting to the new world is not easy, at first.

9 Weeks or 2 Months Old to 11 Weeks

This is still the fourth trimester. Don’t watch the clock, your baby is getting used to their new abilities and is learning more.

Baby, Growth, Parenting

Wonder Week 12, Mental Leap 3


Your baby is starting to perceive their other senses and notices how the world around them changes. They can notice changes, such as a shift in voice tone, light becoming dimmer or the sun going behind clouds. Their world is becoming more organized, but this won’t happen overnight.

Usually, parents notice physical movement most rather than the mental changes happening.

Week 13 or 3 Months to Week 18

They will undergo two growth spurts during this time. One at 3 months of age and another at 4 months old.

Sleep disruption during this time is common and does not reflect on you or your parenting skills.

Baby, Growth, Parenting

Wonder Week 19, Mental Leap 4


For your baby everything is new, everything… nothing is predictable.

When someone drops a rubber ball on the floor, you know it will bounce back up and continue to do so a few times. If someone jumps up, you know they will come back down; you know what follows.

During the previous leaps, your baby was able to see patterns and notice transitions, not only visually but also in sound, smell, texture, and movement. Your baby can understand the world better now as they start to experiment with events.

20 Weeks to 24 Weeks

Your baby is acquiring new skills and learning.

Baby, Growth, Parenting

Wonder Week 26, Mental Leap 5


At 26 weeks of age, they should start to show signs of another mental leap. You will see them trying to do many new things.

Your baby may or may not be crawling yet, but they are a lot more mobile as they learn how to coordinate movement. They are now making connections and understanding the relationships of this world.

The most significant of these is that of distance. We take distance for granted, but it is an alarming discovery for them. The world is suddenly much bigger and considering they have no way of getting to things further than an arm’s length away, sometimes terrifying.

If the mommy goes to the next room, it might as well be China as far as their baby is concerned.

Baby will also undergo a growth spurt at 6 months of age. They may wake up more frequently at night

28 Weeks to 36 Weeks

Your baby may start to wake up more often at night. This is due to development and has nothing to do with you.

Baby, Growth, Parenting

Wonder Week 37, Mental Leap 6


After 37 weeks, you will start to notice that your baby becomes very methodical. They pick up tiny specs off the floor and study them and try to taste them. Your baby may also rearrange food and touch it to feel the texture, or squish a banana just to feel it pass through their fingers. For the mom, this is less than ideal, but you’ll find baby studiously investigating the mess they are making.

Your baby is doing research and categorizing. They can recognize certain objects, sensations, smells animals or even people.

The leap into categories affects all senses.

40 Weeks, 9 Months

Growth spurt. Hang in there, they will wake up more frequently and may be fussier than usual.

Baby, Growth, Parenting

Wonder Week 46 Mental Leap 7


Your baby’s talent for making a mess is ever increasing. During the last leap, you marveled at baby’s knack to shred, toss, squish and disassemble everything in their path.

If you stay alert, you will notice that at 46 weeks old, they do the opposite which is putting things back together.

They have learned that in order to do something successfully, they need to do things in a particular order. They are figuring out how things go together so they can be successful in whatever they do. For example, you may see your baby piling things up neatly or trying to put them together, or when playing with blocks, baby aims before they put a block on top of another.

Week 48

Baby will wake up more frequently at night

Week 52 or 12 Months Old

It’s not you, it’s your baby, and it will pass. You haven’t done anything to create a wakeful baby and sleep is not a milestone though it does feel like an achievement.

Baby, Growth, Parenting

Wonder Week 55, Mental Leap 8


The end of the first year is a significant occasion when your baby is about to become a toddler. Shortly after your baby’s first birthday, they will be ready to experience the world of programs.

If you’re watchful, you will see your baby blossom into a new way of thinking.

You’re probably wondering what programs means so let me explain. Previously, your baby learned sequences; the fact that one event follows another.

Now they are learning “If this then that” decisions. This means that what happens next depends on what just happened.

Want to know what happens in the second year? Check back next week.

Has this post helped you to better understand your baby’s behavior?  Please share in the comments section.

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Founder at LetuKenya
Leah was born and raised in Kenya. She has a degree in psychology and divides her time between article writing, blogging and creating original African pieces. She provides her writing services independently and can be found odesk. When she isn’t hunched over a computer, she’s out being inspired by nature.

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