Geek Trivia

The Exhaustion People Feel After Quitting Coffee Is A Result Of Hypersensitivity To?

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Answer: Adenosine

To anyone who has ever gotten into the habit of drinking coffee and then given it up, this will be a familiar story. You drink your coffee every day, but then you stop drinking it and suddenly you’re tired–more tired than you’ve ever been in your life. Those first few days without coffee come with a level of exhaustion that leaves newly coffee-free individuals feeling like they’re the walking dead. The thing is, the feeling isn’t just in your head or that you’re unused to life without caffeine’s little boost, you’re actually suffering through a period of intense hypersensitivity to a naturally occurring compound in your body. To understand why caffeine withdrawal is so awful, we have to look at the compound caffeine interferes with: adenosine.

Adenosine is a complex compound used in an enormous variety of biological processes both in the human body and throughout the animal kingdom. In the human body, adenosine is a byproduct of many cellular processes, like cellular respiration and the breakdown of Adenosine Triphosphate (ATP) that facilitates energy transfer in the body, that builds up throughout the day. To simplify it, as we go about our day, the level of free adenosine in our bodies rises. Our brain has receptors for adenosine and the more adenosine we have in our system, the more tired we become (making it evolutionarily advantageous to rest and recuperate in response to it).

We hijack this whole process with the introduction of caffeine, however. Caffeine molecules just happen to be close enough to the right shape to antagonize the adenosine receptors in our brains. It blocks the connection and stops the adenosine buildup from stimulating the sleepy response it normally would. As a result of this hijacking, a sort of feedback loop is created where our brain goes, “Wait a minute. The message didn’t get through. Something is wrong. We’ll make more adenosine receptors to bring the system back up to speed.”, but most of those new receptors are also bound up by the caffeine.

When you stop drinking coffee (and stop flooding your brain with caffeine), suddenly all those extra adenosine receptors are no longer bound up by the caffeine and are all flooded with adenosine. The end result is that you feel agonizingly tired because not only are you not getting a nice energy boost from the caffeine, but your brain is now hypersensitive to adenosine and it’s hitting you like truck.

Thankfully, the feeling isn’t permanent. It takes roughly 7-12 days for your brain to self-correct and trim back the excess adenosine receptors. If you can wait it out, day by day, you’ll feel better and at the end of a fortnight, you’ll be back to your old uncaffeinated self.

Image courtesy of Wikimedia Commons.