This post is also available in
Who could go a morning without their ‘black gold’, coffee? This caffeinated drink is for many a very important part of their day. So how does coffee wake you up?
Image by Annelies (CC BY-NC-ND 4.0)
Coffee is popular because it makes us feel ‘awake’. This is something that can be really useful on a Monday morning. There’s even caffeine in tea, although the dosage is less than in coffee. (Yup, theine is the same as caffeine!) So how does the stimulating effect (what makes us wake up) arise in coffee?
Adenosine and caffeine
First, you should know that the molecule caffeine is a lot like the molecule adenosine (take a look at the image below). It has the same double-ring structure, which makes it able to bind onto the same receptors in your body. However, as opposed to caffeine, adenosine is a bodily substance: a leftover product from your body’s energy production. Maybe you can still remember from biology class that your body uses ATP (adenosine-triphosphate) as an energy resource. When this energy resource is used up, adenosine is what’s left over.
Adenosine and Caffeine – [CC BY-SA 3.0], via Wikimedia Commons
Throughout the day, your brain will use a lot of energy and the resulting byproduct of this is quite a bit of adenosine. There are special adenosine receptors that measure your brain’s concentration of adenosine. When these receptors come across too much of adenosine, your body becomes drowsy. Your head has been active for a while, and needs a new energy resource. While you sleep, your body turns adenosine back into ATP, this way it can be reused as an energy the following day. Your body uses an energy byproduct to signal that it’s time for bed!
Because caffeine is so similar to adenosine, it can bind onto the same receptors in your brain. However, it does not give any signal to these receptors. So when many of these adenosine receptors bind with caffeine, no signal is sent to your body. As a result, your brain can’t tell that a lot of adenosine has been used up, so your body doesn’t get tired like it should. This is how caffeine wakes you up!
The effect of caffeine is obviously a little fake, because at some point you will run out of energy. That’s why it’s not a good idea to overdo it by drinking too much coffee.
Caffeine in the mornings
The reason why caffeine works at all is because it hides the pile up of adenosine. So in the mornings coffee shouldn’t really make a difference, that is, if you’ve turned all your adenosine back into energy.
So why is it that so many people love their coffee in the morning? This is because people have grown used to it. By an actual caffeine addiction, adenosine receptors will only respond to caffeine. So by the time you wake up, after not having drunken coffee in while, there is barely any caffeine in your system. You need that first cup of coffee to bring your caffeine levels back up to what you’re used to. So you feel more tired than what you actually are!
So all in all, it’s good to know that without coffee you can still feel energized. Your caffeine dependency disappears after about two weeks, after that you’ll be able to wake up feeling completely fresh and energized, even without a cup of coffee. That is of course, if you go to bed on time…
Written by Annelies.
Edited by Mahur.
Translated by Marpessa.