hey there! welcome to the new episode of Curiosity! A series in which we will answer some of the questions that makes us all curious.

Caffeine as we known , is one of the most widely used drug. According to a survey , over 100,000 tons of caffeine is consumed every year. It's a paradox of life that , some people are trying really hard to fall asleep, and some people are trying as much as they can to stay awake , you might be one of them. Many people use different tricks to stay awake ,alert and not to lose focus. And the most popular way, to stay awake and alert is to drink Coffee or tea. Drinking these to stay awake is more common in Students and Employers. Some how , These hot beverages helps us stay wake, Have you ever wondered Why? and how? , Well, that's what we are going to discuss today. Let's Get started.

How do we Feel Sleepy in the First Place?

Most of us are busy , doing some kind of work through out the day. Some of the works are Physical in nature consuming more energy and some works are mental in nature. One way or another, we are consuming energy throughout the day. Our brain has to ensure that we are up and all our organs are running properly. All these process requires tremendous amount of energy.

There should be a constant supply of energy always to work. Our body Body Breaks down ATP to produce energy. ATP is a very high energy molecule. It stands for Adenosine Triphosphate. The breaking down of ATP produces the Body's Key Sleep Inducing molecule called "Adenosine".

Fig: Adenosine (Credits)

Adenosine is Chemically the back bone of the ATP. The neurons in our brain have perfectly shaped receptors for Adenosine. When More Adenosine is produced by Breaking down of ATP, they docks to these receptors in our Brain. After docking with the Receptors, Adenosine triggers a cascade of biochemical activities. This process Slows down the Nerve activity. And over time, We start to feel drowsy. Drowsiness is not sudden, but it creeps on us very slowly through out the day. This is the reason why we feel exhausted at the end of the day.

So, Why Does Caffeine keep us Awake?

Coffee is one of the most popular beverage to help us be awake and alert. Mostly used by Students to stay awake during exams, or Employers to finish their work. One way or another, it helps us focus, be alert and most importantly stay wake. But what really happens to keep us awake?

Well, Caffeine, Comes into action when you drink coffee, or tea or any beverage containing caffeine. To a nerve cell in the Brain,the molecular structure of Caffeine looks very similar to that of Adenosine. Caffeine therefore binds to the Adenosine receptors in the neurons. How ever, like adenosine, caffeine doesn't slow down the nerve activity. Caffeine is also called as the "Adenosine receptor antagonist". They block the adenosine receptors.

Fig: Caffeine binding to Adenosine Receptors (Credits)

In short, Adenosine is the inhibitor of the nerve activity, causing sleepiness. Caffeine inhibits the inhibitor, so it's a Stimulant.

Other Effects of Caffeine

For Headache

Caffeine also causes the blood vessels in the brain to constrict because adenosine is already blocked to dilate them. This is why , consuming caffeine relieves headache in minutes and keeps you fresh. Also because of these many headache medicines contains caffeine.

For Positive Feelings

Caffeine can also Boost happiness and positive feeling. In some neurons, adenosine receptors are linked to dopamine receptors. One of the Dopamine's role is to promote the feeling of happiness and pleasure. When actual adenosine binds to its receptor, it's size makes dopamine harder to fit in. There fore, Dopamine effects are not observed. But when Caffeine docks into the receptors, it makes dopamine easier to fit in its receptor. This lifts up your mood. This can have some long term benefits too, reducing the risk of disease like Parkinson's , Alzheimer's etc.

For Adrenaline Rush

Also, when caffeine increases the neuron firing in the brain. The pituitary gland senses it, and releases its hormones to tell the adrenaline gland to produce adrenaline. Now Adrenaline is of course the "Fight or flight" hormone and has number of effects on your body. Some of the effects are , your pupil dilates, heart starts beating faster, Blood flow increases to muscles , Increase in blood pressure, Blood flow to the stomach slows down, Muscles tighten up. This is the reason why your hands get cold and you feel excited after consuming a big cup of coffee.