It would be no surprise if you felt the need to nod off or catch a quick nap during the day, even feeling lethargic during productive tasks, however when it’s the time to sleep at night you can’t drift off? — It’s so frustrating, I know!! If you can relate, this blog post is for you. 

People who struggle with sleep have a really hard time being compassionate with themselves when they do experience difficulties sleeping. There are many different reasons somebody might be having difficulties sleeping. I am not sure what yours is. As the saying goes “You’re the expert on you.” However, this post aims to introduce you to important chemicals which make up the sleep cycle, to increase your knowledge on sleep.   

Now you may say, you already tried to establish a healthy sleep routine but felt like you need more? We will dive into this topic and break down how to achieve a quality sleep which can develop into healthy sleeping habits.

Our discussion today will focus on:

• Sleep pressure 
• Introducing adenosine 
• How to artificially mute signals of adenosine 
• Caffeine on sleep pressure
• Deeper into adenosine 

Sleep pressure

Two questions to start with. Do you ever wonder why you will get tired this evening? And why tomorrow morning when you wake up will you be free from that tiredness?

(Source: Heydar Hasanov, 2024)

Well, it turns out that there are TWO independent but very complementary forces that explains why exactly this is the case! The first of those is called “sleep pressure” and the second is called your “circadian rhythm.”

From the moment that you wake up, a chemical has been building up in your brain and the longer that you are awake the more of that chemical will continue to build up and the more of that chemical that builds up the sleepier you will feel. This is what we call “sleep pressure” and that chemical is called ADENOSINE 

Introducing adenosine 

You can think of this chemical almost like a chemical barometer that continually registers the amount of elapsed time since you woke up this morning. So it’s a chemical signal that helps tell your brain and your body how long you’ve been awake. And when those levels get high enough, it will tell your brain, it’s time to go to bed because you are sleepy. 

Now adenosine accomplishes this sleepiness using a very clever action effect. High levels of adenosine in the evening will simultaneously turn down the volume in the wake promoting region and it will crank up the dial on the sleep-inducing regions of the brain. 

At that point with the adenosine concentrations peaking there should be an irresistible urge of slumber that will take hold of you. This happens to most of us somewhere after TWELVE TO SIXTEEN hours of being awake. 

How to artificially mute signal of adenosine 

I know it feels like a cruel joke that sometimes we battle with exhaustion and sleepiness during the day when we have responsibilities to fulfill, only to be wide awake and staring at the ceiling when bedtime arrives.

The good news: you can however artificially mute the sleep signal of adenosine by using another chemical that makes you feel more alert and more awake. You SURE know this chemical, “caffeine.” it’s no coincidence that two things sound quite similar, “caffeine” and “adenosine,” it’s down to the systems in the brain that they both act upon. 

Now don’t worry, in a separate post, we will talk all about the effects of caffeine on sleep but here we are going to explain caffeine effects on adenosine, in other words on sleep pressure!

Caffeine on sleep pressure  

Caffeine works by successfully battling with adenosine for the delightful privilege of latching onto what we call the “adenosine welcome sites” in the brain or in other words “adenosine receptors” 

With its pretty sharp elbows, caffeine will nudge adenosine out of the way and will latch onto those adenosine receptors. But unlike adenosine, caffeine is not going to stimulate those receptors to produce more sleepiness, instead caffeine blocks and effectively inactivates those receptors and acts like a masking agent. It will be the equivalent to sticking your fingers in your ears to shut out that loud sound of that tiredness, of that adenosine sleepiness. By hijacking and occupying those receptors, caffeine effectively blocks the sleepiness signal that would normally be communicated to your brain by the adenosine, so that’s how caffeine works, it blocks the signal of sleepiness. 

WARNING! This does not mean or suggests you should start drinking 10 cups of caffeinated drinks to stay up during the day, more on the effect of caffeine must be discussed carefully. 

Deeper into adenosine

Let’s come back to this chemical. The buildup of adenosine during the day is only one half of our story when it comes to sleep pressure. That explains why you feel tired towards the end of the day, what it does not explain however, is why you DON’T feel tired or at least you shouldn’t feel tired the next morning when you wake up — and this is where sleep enters our story as a new lead actor in the second half of the post.

Now the question is: what happens to all of that accumulated adenosine once you fall asleep?

Well, it’s during sleep that a mass evacuation of adenosine gets underway, this means; its during sleep that the brain has a chance to degrade and remove the day’s weight of adenosine and across a night, sleep will essentially lift the heavy weight of sleep pressure of your brain lighting the adenosine load. After approximately eight hours of healthy sleep in the average adult, the adenosine purge is complete, with that clearance of adenosine together with changes in your circadian rhythm, you should naturally wake up feeling refreshed as long as your sleep has been long enough and of good quality. You will feel restored by your sleep, and with that restoration, you are now ready to face another sixteen hours of wakefulness. 

Conclusion  

All in all, that is the story of; sleep pressure, of how it works and how you can try to block it with caffeine. Now that you have a better understanding of how the cycle works, the next posts will focus on learning about your circadian rhythm, the effects of caffeine on sleep and tools to enhance better sleep at night when you cannot drift off.