Coffee is the world's most popular psychoactive substance. Over two billion cups are consumed every day, making it one of the most traded commodities on earth. But the chemistry behind what makes coffee so effective at waking us up is far more complex than most people realize.
Caffeine works by blocking adenosine receptors in the brain, preventing the buildup of the neurotransmitter that makes us feel sleepy. The origins of this beloved drink trace back to the highlands of Ethiopia, where legend holds that a goat herder named Kaldi first noticed his goats becoming unusually energetic after eating certain berries.