Why does caffeine keep awake?

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Thursday, 17/11/2016 10:11

Why does caffeine keep awake? 

Have you ever wondered why caffeine keeps you stay awake? This article will give you the answer for how caffeine works and how it affcects on your body.

 If you read the HowStuffWorks article How Sleep Works, you learned that the chemical adenosine binds to adenosine receptors in the brain. The binding of adenosine causes drowsiness by slowing down nerve cell activity. In the brain, adenosine binding also causes blood vessels to dilate (presumably to let more oxygen in during sleep).

Why does caffeine keep awake?


Why does caffeine keep awake? 

Adenosine is produced by your daily activity. For example, the article How Exercise Works discusses how muscles produce adenosine as one of the byproducts of exercise.

To a nerve cell, caffeine looks like adenosine. Caffeine, therefore, binds to the adenosine receptors. 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. You can see that caffeine also causes the brain's blood vessels to constrict, because it blocks adenosine's ability to open them up. 

When consuming a big amount of caffeine, there will have some effects on your body:

  • Your pupils dilate
  • Your breathing tubes open up (this is why people suffering from severe asthma attacks are sometimes injected with epinephrine)
  • 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 pressure rises
  • Blood flow to the stomach slows
  • The liver releases sugar into the bloodstream for extra energy
  • Muscles tighten up ready for action

So, now do know why you feel your hands get cold, your muscles tense up, excited and your heart beat increasing after you consume a cup of coffee?

Check out for more news about the best way to stay awake, news about caffeine addiction and more.


Elly Green

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