Caffeine is probably the most widely consumed stimulant in the world, it's widely found in tea. coffee and soft drinks. People use it to wake themselves up in the morning or to give their day a burst of energy. But how does caffeine actually make you feel less sleepy?
Caffeine is found in plants leaves,beans and seeds as a defense mechanism. Plants have evolved the presence of caffeine as a deterrent for small insects. If an insect ingests a high concentration of caffeine then it can be toxic. The insect in turn have evolved taste receptors which allow them to identify and avoid things which contain caffeine. It turns out that caffeine is also a key component in the flavour profiles of tea by providing bitterness and astringency.
How caffeine reacts with our body to reduce tiredness is all about how it interacts with receptors in our brains. If you think back to your high school biology and use the lock and key analogy; the receptors are the locks and ineracting molecules are the keys. One of the keys linked to tiredness is called adensoine, when it unlocks the receptor it causes the body to relax muscles and induce sleepiness. It is infact one of the key sleep regulating molecules and will slowly build up in your nervous system through the day to allow you to fall asleep at night.
When you drink tea the caffeine from it is absorbed by the small intestine and can enter the bloodstream to your brain within an hour. Caffeine has a similar chemical structure to adensoine so when it enters your brain it actively competes for receptor space with the adenosine. This process means than less receptors are connected to adenosine and thus sleepiness is reduced. After a few hours your body starts to metabolize the caffeine molecules and the adenosine's competition for receptor space reduces and tiredness begins to build again, unless you have another cup of tea of course.
One final important note to finish on is that the amount adenosine does not reduce when drinking caffeine, infact it just creates a backlog of the molecules. The only way to get rid of them, is to have a good sleep. So it's is not a substitute for a bit of shut eye but caffeine is great at waking us up in the morning and getting through tiring days when we need it.
The benefit of getting your caffeine boost from drinking tea rather than coffee is that you reep the benefits of tea's extra super power L-theanine. Click here to read our next blog to find out more about this amazing amaino acid.