How Does Caffeine Keep You Awake?

How Does Caffeine Keep Me Up Late at Night?

In short, it's all about two words: Brain Chemistry.

You see, our “Brain Chemistry” have a bunch of neural chemicals in our brains that are in charge of regulating this balance and keeping us awake or asleep and controlling our level of energy, alertness, fatigue, etc.

Caffeine is a fat-soluble chemical that easily passes from your bloodstream into your brain tissue. Our brain activity is controlled by chemicals called neurotransmitters, which either stimulate brain cells or quiet them.

Adenosine is an important one of those “quieting neurotransmitter”. Adenosine is an “inhibitory neurotransmitter” that pushes you towards the “fatigued/sleepy” end of the spectrum. In short: more adenosine means more sleepy. If you have lots of adenosine in there, you are going to feel sleepy, fatigued etc. If you have less adenosine it means you will feel less sleepy.

Enter Caffeine

Caffeine molecule

Caffeine causes most of its biological effects via antagonizing all types of adenosine receptors (ARs): A1, A2A, A3, and A2B and, as does adenosine, exerts effects on neurons and glial cells of all brain areas. In consequence, caffeine, when acting as an adenosine receptor antagonist, is doing the opposite of activation of adenosine receptors due to the removal of endogenous adenosinergic tonus. Caffeine attaches to adenosine receptors on your brain cells, blocking the quieting effect of this neurotransmitter. 


The effects of caffeine on our brain chemistry” do not just stop there. The increased activity of our brain cells under the influence of caffeine leads to a secondary rise in the amount of epinephrine in the body. Epinephrine is the "fight or flight" hormone, which has stimulating effects on our brain and body. Which basically means that you will not have the feel sleepy fatigued feeling.

Does Caffeine actually GIVE energy?

No, the surge of energy you experience from drinking coffee comes from the mild stimulant effect of caffeine on your brain more particularly when acting as an adenosine receptor antagonist. In fact, espresso coffee contains a minuscule number of calories and is, therefore, a negligible source of energy from a nutritional standpoint. The net effect of caffeine, therefore, is stimulation. It is only a perceived increase of "energy" because you feel more mentally alert.

Real Caffeine Power Nap 

When you drink a cup of coffee, the drug it contains – caffeine – takes effect within about 15 minutes.

According to the University of Michigan Health Service, the stimulating effects of caffeine can start as early as 15 minutes. After drinking caffeine, it usually reaches its peak level in your blood within one hour and stays there for four to six hours.

This means that if you really wanted to maximize the caffeine effect, you should drink a cup of coffee – take a power nap – and wake up after 30 minutes fresher than you would have you only taken a power nap.

brain chemistry caffeine

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