Updated: Sep 10
In all of my experience as a sleep consultant, I can't even count the amount of times I have heard the following:
He's been awake for hours and is SOOO tired, why won't he just fall asleep?!?!
Many parents assume that because their children sleep when tired, they will really sleep if they're really tired. I have talked to some parents that even try to keep their children up longer in hopes that they will be tired enough to sleep longer and better. The logic behind that thinking is not completely lost on me, especially as a parent who has gone through her own share of sleepless nights. When your child isn't sleeping well, you will try anything...I get it. However, the science behind it shows flaws in that logic.
What is Over-tiredness?
Well, I am an educator by trade, so let's break the word down, my students. The prefix over- means "above; too much; beyond in time." The suffix -ness means "the state or condition of." Add those to the root word tired and you have "the condition of being tired too much." Over-tiredness isn't just being really tired. It means you're too tired, above and beyond the amount of tired you should be. So, back to the original question I get all the time: if a baby is above and beyond tired, why won't he just go to sleep?
Melatonin verses Cortisol
The main reason over-tiredness causes trouble falling asleep is due to the natural production of hormones in the body. When your child is becoming tired, his body starts to produce #melatonin. This is the hormone that promotes sleep. If you put your child to bed at this point, his body will be giving him what's needed to help him fall asleep.
However, if you don't put your child down for sleep at this point, then his body goes into reaction mode. It thinks, "Hmm...if it's not time for sleep, then it must be time to stay awake." Therefore, the body stops producing melatonin and begins producing cortisol instead.
Cortisol is the hormone that helps us wake up. When your child is overtired, his body produces #cortisol to try and help him stay awake, thinking that's what is needed. Then, when you do try to put him down to sleep, his body is now giving him the wrong hormone. Cortisol will cause him to fight sleep.
The result is usually a cranky mess. Your child is definitely tired and needs sleep, but his body is now trying to keep him awake. Trust me, he's just as frustrated about it as you are. Have you ever felt so exhausted and then crash into bed only to find that you're now wide awake? It's so annoying! Parents assume that you should be able to lay an overtired baby down and he will easily go right to sleep. On the contrary, overtired babies often need more help falling asleep because they are fighting resistance from their own body.
Overtired babies often need more help falling asleep because they are fighting resistance from their own body.
Over-tiredness can also cause more night wakings and early morning wake-ups. Our bodies all experience a natural surge of melatonin at night and then a natural surge of cortisol in the early morning. When this natural flow of hormones is regularly off kilter, sleep in general will be affected.
This can cause a vicious cycle of sleep issues because the body is just not able to figure out the correct times to release these hormones. Kids can very easily become chronically overtired...which causes sleep problems...which then adds to the over-tiredness...and the cycle continues. Yikes!
Appropriate Wake Times
Babies change a lot in the first year of life. When they are newly born, they can only stay awake for about 45 minutes at a time. By the end of that first year, they can stay awake for about 3.5-4 hours before needing more sleep. The key to making sure your child doesn't get overtired is to put him down to sleep after an appropriate wake time for his age. Every. single. time.
Download my Sleep Times Chart below for a guide on wake times, number of naps, and needed sleep amounts for different ages.
Sleepy signs are also helpful to know because every child is different. Appropriate wake times are averages, but you also don't want to push your child to some specific wake time if he's showing clear signs of being tired before then. Here are the most common sleepy signs, as well as the signs your child has reached the overtired stage:
It takes some patience and practice, but you can watch your baby to learn what his main sleepy signs are. When you see them, and it is near the appropriate wake time for his age, put him down for sleep to avoid over-tiredness. If your child does reach the overtired stage, you will know for next time that his wake window is a little shorter. This will clue you in on when to start looking for those sleepy signs.
The key to making sure your child doesn't get overtired is to put him down to sleep after an appropriate wake time for his age. Every. single. time.
A Note about Newborns
The body's circadian rhythm usually doesn't start developing until around 6 weeks of age. Melatonin production doesn't fully develop until closer to 12 weeks. So, a #newborn spends his first 3 months of life working on developing these. What this means is that most newborns need help falling asleep regardless of whether or not they are overtired because their bodies aren't yet helping them with melatonin production. With that said, you should absolutely still be aware of your newborn's average wake times and be working to put him down when sleepy.
Also, newborns will not exhibit all of the sleepy signs above. For example, rubbing the eyes is not something a baby can developmentally do in those early weeks. Don't get frustrated if you are having trouble seeing sleepy signs in your newborn. Focus on the wake times until those signs begin to develop. Newborns need a lot of sleep. As mentioned above, young newborns can only stay awake for 45 minutes. Closer to the end of the newborn stage, it will be about 1.5 hours.
My newborn sleep guide gives much more detail about all of this. It also explains what you can do to help their circadian rhythm and hormone production develop as quickly as possible...among so many other helpful things to know! Click here for more information on that.
Over-tiredness can be a vicious cycle that causes a variety of sleep issues. To avoid this, make sure you are putting your child down for sleep after the appropriate wake time for his age.
~Ashley Bell, pediatric sleep consultant