Millions of people over the world start their day with an aromatic cup of coffee generally to wake them up. Coffee contains caffeine which is the stimulant that interacts with the body to make you feel more alert. How Coffee works and its benefits Caffeine works as an antagonist (block receptors) of adenosine receptors in the brain. Caffeine mimics the natural neurotransmitter; adenosine, and blocks the receptor, preventing adenosine from binding to the receptor and slowing the nervous impulses. In turn this makes the nervous impulses quicker and the brain works faster. Also caffeine can relieve headaches and migraines since it binds to adrenergic receptors on vascular muscle cells which cause them to constrict instead of dilating.