How Over-Tiredness Leads to Sleep Issues



I recently asked on instagram for issues parents are facing with their little ones sleep. I continue to see a trend among the results. Parents wanted to learn more about why it’s so hard for an overtired baby to fall asleep and stay asleep. I completely understand why anyone would like to learn more because it can be pretty confusing, considering that as adults, we typically sleep better when tired. The opposite is true with our children.

That’s because children are more sensitive to over-tiredness than adults are. When we restrict ourselves from sleeping when we’re tired, our bodies assume there must be some sort of danger. With their extra sensitivity, our little ones’ bodies enter a fight-or-flight state when this happens.

In this state, the body starts producing cortisol, which is the stimulating “alert” hormone that keeps them awake. So our little ones build up the cortisol and there is nowhere for this cortisol to be turned into energy to go! So cortisol — the hormone responsible for keeping us awake — gets bottled up in our kiddos bodies and it takes a while to process. With this excess of cortisol working through the system, it makes it much harder for our kiddos to fall asleep and stay asleep. sounds pretty rough, huh?

Let’s walk through a few different issues connected to over-tiredness….

Night Wakings


With an overtired child, you’re typically going to see that it will take longer for them to fall asleep. Then, the irregular wake-ups in-between their sleep cycles may take a turn for the worse.


The thing about sleep cycles is that 1. we all experience them 2. We all wake up briefly in-between sleep cycles, and 3. We typically don’t remember the wake-up because of how brief it is and we’ve learned how to string our sleep cycles together (in other words, as adults, we are sleep trained!). For an overtired child, the brief wake-ups in-between each sleep cycle is going to feel much more significant than just a toss or turn in the night.

Some children might be able to sleep through the night even though they’re overtired. But, typically they end up waking early. The reason for this is because any extra cortisol in their system will build up early in the morning. Our bodies naturally start producing cortisol early in the morning to prepare for wake-up. So for an overtired child, any extra cortisol accumulated from pushing their sleep limit is now very built up with the natural morning production, making them ready to rise around 4:35/5:00 AM.


If you suspect your child is waking up early because they’re overtired, I would suggest moving their bedtime up by about 30-60 minutes and see if that makes a difference. Be sure you give it a few days because they might be carrying around a little bit of a sleep deficit. So until they work that off, their body’s going to continue to produce that extra cortisol.



The cortisol effect makes naps more challenging as well. Naps are difficult to begin with because during the day, there is a lack of melatonin in your child’s body.


Melatonin is the opposite of cortisol. It’s the other hormone our bodies produce to regulate our sleep and awake cycles and it’s known as the “sleepy” hormone. It’s also sometimes called the “Night Time” hormone because our bodies only produce it in darkness (typically, at night).


Sleep pressure is the effect from a chemical called adenosine. Our bodies produce adenosine while we’re awake. When adenosine attaches to neurons in our brains, it makes us sleepy. As we sleep, our body rids itself of the adenosine and prepares to repeat the cycle all over again. So, during the day when there’s no melatonin, we’re just banking on adenosine for our kiddos to nap well.

Use Wake Windows


This is really important! If your child’s body is producing cortisol because you’re waiting too long to put them down, then it’s going to be harder for them to fall asleep and they’ll likely take a short nap — about a 30-45 minute nap, because that is the length of a sleep cycle for a child. I recommend following your baby’s recommended wake windows for their age range.


  • Use the shorter end of the wake window in the morning after wake-up, before the first nap.
  • If that first nap is a good nap (a good nap in my book is anything over an hour), then you can increase the next wake window to the longer end.
  • Follow that rule of thumb for the remainder of the day, even before bedtime.

Watch For Sleepy Cues


Now, I don’t recommend relying completely on wake windows. You also want to watch your child. Every child is different, and you know your child best. So keep an eye out for their sleepy cues.

The best time to put your child down is when they’re exhibiting what I call Sleepy Cues Stage 1:

  • Not interested in activities
  • Averting their eye contact
  • Turning their head from side to side
  • They have that dazed look in their eyes

This is the perfect time to put your child down for a nap. That said, if they start showing those signs about a half hour before the wake window expires, try changing up activities first because your child may just be bored! Or give them a little boost of energy — if they’re eating solids, give a little bit of fruit puree. Or bring them by a window for a little extra dose of sunlight. Sunlight actually produces cortisol! We have little receptors in our eyes that detect sunlight, and then they tell our body to produce cortisol. Cool, right? Although I know we don’t want excessive cortisol which is caused by over-tiredness, it is ok to get a bit of a natural cortisol boost through the sun.

If those techniques don’t work to keep your child awake until the wake window expires, then your child is definitely ready for a nap. Go ahead and put your child down.

Your child is definitely ready for a nap if they exhibit Stage 2 Sleepy Cues:

  • Yawning
  • Rubbing eyes

Go ahead and put your child down for a nap.

You know you’ve extended your child too long if they exhibit these Stage 3 Sleepy Cues:

  • Falling asleep
  • Crying
  • Arching back – thrusting their body

The next time you put your child down for a nap, you’ll want to shorten the next wake window.


I hope this is helpful and explains why over-tiredness leads to sleep issues. My goal is for you and your family to have the tools you need to help your child get the rest they need to be their best.

If you have any questions or want to dive deeper into sleep issues your little one is facing, please feel free to send me a DM on Instagram – or send me an email

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How Over-Tiredness Leads to Sleep Issues


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