Adenosine

Adenosine regulates neural activity and maintains the balance essential for normal brain function. By inhibiting adenosine, chocolate produces increased wakefulness, alertness, and mental energy, similar to coffee but milder. Adenosine is a neurotransmitter that acts as the brain's braking mechanism. Adenosine is a sleep-promoting compound in the brain that caffeine and related compounds in chocolate block. Caffeine occupies adenosine receptors, preventing adenosine from binding and blocking the sleep signal. Adenosine is a neurotransmitter that accumulates throughout the day and promotes sleepiness by binding to receptors in brain cells. Stopping caffeine allows adenosine receptors to upregulate back toward baseline, which explains why withdrawal symptoms resolve after approximately one week. Chronic caffeine use causes the body to downregulate adenosine receptors, which is the key mechanism underlying caffeine tolerance.