How Caffeine Affects Sleep

Doc Parsley
January 11, 2021
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How many times growing up do you remember hearing your parents tell you “no more soda today, that caffeine isn’t good for you?”

Meanwhile, they were sipping on their own soda…or coffee…or energy drink.

Here’s the thing: caffeine is not good for sleep, for anyone. Period. 

It just might show up as damaging for kids sooner, because sleep is so vital to all of the growth their bodies are trying to put them through. 

So, let’s talk about how caffeine affects sleep in kids – and adults. 

There’s not an active process that makes you fall asleep

First thing’s first: you need to understand that we don’t really have a scientific definition for sleep. 

That might sound crazy, but it’s true. 

There’s not actually a hormonal process, a physiology shift, or anything that happens in the body to “bring on” sleep. 

The process of going to sleep is simply the act of taking away the things that keep us awake.

That’s why a bedtime routine is so important – we’re removing: 

  • External stimuli like:
    • Sounds
    • Bright lights
    • Uncomfortable temperatures
    • Rough textures
  • All of the things about your day that stress you out, by focusing on something like a book or a puzzle
  • “Busy” work for the body, like digestion (hopefully you’re not eating too close to bedtime!)

And on a cellular level, there are plenty of hormones and molecules meant to keep you awake (like cortisol and ATP). 

But nothing specifically is released or altered to bring on a state of sleep. 

So, the closest thing we have to a working scientific definition of sleep is “the absence of being awake.” 


How caffeine affects sleep in people

The body’s energy source

Now, I just mentioned that there are a few things in the body that prevent sleep. 

A key piece of that puzzle is ATP, which stands for adenosine triphosphate (don’t worry, I’m calling it ATP for the rest of this article).

But the name tells us what this molecule is made of: 1 adenosine, with 3 phosphates attached to it.

This is important because ATP is the source of energy for every cell in our body.

It doesn’t matter what that cell’s function is. They all run on ATP. 

And the way the cells get energy from ATP is by breaking off one of those molecules of phosphate, leaving an ADP (adenosine diphosphate) molecule. 

Once ATP is used up, the cells will break off another phosphate from the ADP, leaving us with AMP (adenosine monophosphate). 

And last but definitely not least, the cells will pull off that final phosphate from AMP to leave us with a bunch of free-floating adenosine. 

If we imagine each individual cell like a person, this is an easy concept to grasp.

Each human ingests fuel (food), does work (everyday life), and removes waste (exhaling, urinating, defecating, etc.)

The phosphates are the “food” for the cells. 

Now, here’s where the sleep cues come in. 

Once we’ve reached a sufficient load of free-floating adenosines in the body, there are receptors floating around that detect these high levels of adenosine. 

Those receptors send the signal to the brain and body that we need to rest in order to restore the body’s levels of ATP.

Keep this in mind for the rest of the article – it’s a key piece of the sleep puzzle. 

How caffeine affects sleep in adults

We need to go to sleep to recover

Going to sleep is the only way we get any repair done in our body. 

This includes the above mentioned ATP regeneration – we simply can’t keep up with the demand for more energy creation while we’re awake, so we need to sleep and allow the cells to essentially recharge themselves. 

It’s a pretty clever mechanism of evolution, too. 

The more active you are, the less time you have before you’ll need to sleep again and restore the necessary ATP. 

So, the general breakdown for an average day is 16 hours awake for every 8 hours of rest.

But, this can change if you have a more active day. Maybe sometimes you’ll have 15 really active hours and need 9 hours to recover, and so on. 

And when you’re young, you’re usually much more active.

Not only are you running around like kids do, but you’re also growing and learning new things daily at an incredible pace. 

In general, they need anywhere from 9-12 hours of sleep each night. 

This goes all the way through the teenage years, which I mention in my blog about puberty – I remember having almost a reversed sleep schedule of 10 hours awake and 14 asleep at that age. 

The reversal of your sleep schedule makes sense when you’re young, because every day as a kid you wake up stronger, smarter, faster, and physically improved in some way from the day before.

That’s what sleep does for someone who’s still growing up. 

Once you’ve reached adulthood, sleep is intended for maintenance of all the things you built up in your youth…as well as prevention of loss.

Yeah, I know that doesn’t sound as fun, but it’s better than having no way to make repairs! 

The point of all this is to say that when kids miss out on sleep, they’re hindering their growth potential.

And when adults miss out on sleep, they’re just encouraging a faster aging process. 

How caffeine affects sleep in kids

Caffeine affects sleep in kids & adults in the same ways

Now, the moment we’ve all been waiting for: how does caffeine affect sleep in all of this?

Well, think back to that adenosine receptor I mentioned earlier. 

Its only job is to detect when we have too much free-floating adenosine in the body, meaning we don’t have much ATP left for cell fuel. 

Caffeine blocks those receptors. 

This means that instead of allowing adenosine to bind with those receptors, sending the “get tired” signal to the brain and body, caffeine binds there instead and the receptors can’t tell the body that you’re almost out of fuel.

This works for a little while, but it’s also why you get a “coffee crash” after the caffeine inevitably wears off and exposes all of that free-floating adenosine to its receptors. 

You’re essentially blocking your normal physiology from knowing it’s time to recover. 

In kids, this can literally hinder vital growth and repair time for them to be as strong and smart as possible. 

In adults, it’s just allowing degeneration to occur earlier than it “should” if you were getting enough sleep.

So, the long story short is this: I don’t recommend caffeine for kids, ever. 

And in adults, I strongly encourage you to finish that last cup of Joe by noon each day. 

Our bodies are already working hard enough to keep us alive as it is, why make it more challenging? 

If you or your kids are still having a hard time sleeping well, even after caffeine is out of the picture, check out my Sleep Remedy and Sleep Remedy Kids. 

These are non-addictive sleep supplements that encourage melatonin production in your own body.

Find out more about Sleep Remedy & Sleep Remedy Kids here

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