Written for eufic.org. Published in July 2024.

Caffeine is a natural stimulant that belongs to a class of compounds called xanthines. The most well-known source of caffeine is the coffee bean, the seed of the Coffea plant. Other natural sources include the tea leaf, kola nut, cacao pod, and guarana berries. Caffeine can also be produced synthetically in laboratories. Synthetic caffeine may be used in products such as energy drinks, supplements, and cosmetics. People commonly consume caffeine to relieve or prevent drowsiness and to improve concentration and focus.

How does caffeine work ?

Due to its ability to dissolve in both fat and water, caffeine can easily cross the blood-brain barrier .¹Once it has reached the brain by traveling through the bloodstream, it interacts with specific sites in the brain known as adenosine receptors.¹ Adenosine is a neurotransmitter that promotes sleep and relaxation by slowing down nerve activity. Caffeine binds to the adenosine receptors without activating them, effectively blocking the action of adenosine, and leading to increased neuron firing in the brain. This increased neural activity triggers the release of other neurotransmitters such as dopamine and norepinephrine, which enhance arousal, alertness, and attention. Caffeine also stimulates deeper breathing by enhancing the brain’s response to carbon dioxide.¹