Coffee can help people feel less tired and increase energy levels
This is because it contains a stimulant called caffeine, which is actually the most commonly consumed psychoactive substance in the world.
After you drink coffee, the caffeine is absorbed into the bloodstream. From there, it travels into the brain .
In the brain, caffeine blocks an inhibitory neurotransmitter called Adenosine.
When that happens, the amount of other neurotransmitters like norepinephrine and dopamine actually increases, leading to enhanced firing of neurons .
Many controlled trials in humans show that coffee improves various aspects of brain function. This includes memory, mood, vigilance, energy levels, reaction times and general cognitive function
Info from Authority Nutrition Here