Do you remember the late nights during exams when the only thing on your mind was crawling into bed? And how a single cup of hot coffee kept you up all night with your books? Let’s find out how.
Coffee’s ability to keep you awake is all thanks to its primary constituent – caffeine. Caffeine works by changing the chemistry of the brain. It blocks the action of a natural brain chemical that is associated with sleep.
How sleep sets in
Drowsiness is caused by the slowing down of nerve cell activity in your brain. A chemical called adenosine binds itself to the adenosine receptors in our brain. It is this binding of adenosine that causes the slowing down of nerve cell activity. Where does Adenosine come from? It is produced by your daily activity. For example, muscles produce adenosine as one of the byproducts of exercise.
How caffeine prevents drowsiness
Here is the amazing fact about caffeine that makes it so effective against drowsiness: To a nerve cell, caffeine looks like adenosine!
Therefore the adenosine receptors bind to the Caffeine in your coffee, instead of the actual adenosine. However, it doesn’t slow down the cell’s activity as adenosine would. The cells cannot sense adenosine anymore because caffeine is taking up all the receptors adenosine binds to. So instead of slowing down because of the adenosine level, the cells speed up!
With caffeine blocking the adenosine, you have increased neuron firing in the brain. The pituitary gland sees all of the activity and thinks some sort of emergency must be occurring, so it releases hormones that tell the adrenal glands to produce adrenaline (epinephrine). Adrenaline is, of course, the “fight or flight” hormone and it has a number of effects on your body:
- Your pupils dilate
- Your breathing tubes open up
- Your heart beats faster
- Blood vessels on the surface constrict to slow blood flow from cuts and also to increase blood flow to muscles
- Blood flow to the stomach slows
- The liver releases sugar into the bloodstream for extra energy
- Muscles tighten up ready for action
In short, it banishes drowsiness and gets you all charged up.