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Overtired Babies. How Cortisol Affects Their Sleep.



a tired newborn baby yawning

Babies don't come with low battery notifications (but how great would that be!!)

However, If you've been around an overtired baby you'd likely know the signs; incessant crying, stiff body, and a crankiness that seems impossible to soothe and get to sleep. But have you ever wondered why your child behaves this way? If they are tired, why can't they just sleep? The answer lies in the link between overtiredness and cortisol, the stress hormone.


What is cortisol and how does it affect babies?

Cortisol, often referred to as the stress hormone, it is a natural chemical produced by our bodies in response to various stressors. Cortisol also plays a crucial role in regulating our sleep-wake cycle, helping us feel alert during the day and ready to sleep at night. However in babies it operates a little different and can cause major disruption to their sleep.

When a baby becomes overtired, they experience a cortisol and adrenaline spike. These elevated levels lead to increased irritability, stress & energy making it even more challenging for them to fall asleep. This becomes a vicious cycle – the more overtired they become, the harder it is for them to settle down and rest.


Overtired-ness. A vicious cycle.

  1. Missed Sleep Cues: Babies have subtle signs that indicate they're ready for sleep, not all babies have the same signals but if you watch carefully you can start to recognize your babies tired cues. Signals such as rubbing their eyes, yawning, or becoming less engaged with their surroundings.

  2. Sleep Deprivation: When babies don't get enough sleep, their bodies produce even more cortisol, which can disrupt their natural sleep-wake rhythm.

  3. Trouble Falling Asleep: High cortisol levels can make it difficult for babies to relax and fall asleep, leading to more restlessness and fussiness.

  4. Reduced Sleep Quality: Overtiredness can result in fragmented sleep, reducing the overall quality of rest your baby receives.

Breaking the cycle. Getting better sleep


I work with a lot of overtired kiddos. My mission as a sleep consultant is to help parents create healthy sleep habits that work for their kids. What does that usually look like?

  1. Sleep Cues & Wake Windows: Learning to identify your baby's sleep cues & what their individual wake window tolerance is: is the first step in preventing overtiredness. By responding promptly to cues & focusing on wake winows, you can help your baby settle into sleep before cortisol levels rise.

  2. Bedtime Routine: A consistent and calming bedtime routine can signal to your baby that it's time to wind down. This can help reduce cortisol levels and prepare them for a peaceful sleep.

  3. Establishing a Sleep Schedule: Implementing a consistent sleep schedule can regulate your baby's internal clock, promoting better sleep quality.

  4. Independent Sleep Skills: Your babies ability to fall asleep independently makes a big difference in their ability to connect their sleep cycles without assistance. If babies can't connect their sleep cycles on their own, they can spend a lot of time in-between cycles awake when they should be sleeping, which isn't the quality sleep and restorative rest that they need.

Understanding it all,


Trying to soothe an overtired baby can be really frustrating, they are fed, dry and warm; hands up if you've asked "why can't you just fall asleep" Hopefully understanding the cortisol-baby connection can help provide some insight and make things feel a bit more manageable.

Recognizing tired signs can help get a head start on trying to get babies settled. Introducing healthy sleep habits can help your baby get the restful sleep they need, If you're struggling getting these habits in place, I'm here to help.


xo Erin


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