For example, 2021 research explains that caffeine increases alertness by blocking the brain chemical adenosine (which is what makes you feel tired), while at the same time triggering the release of adrenaline, known as the fight-or-flight hormone.

例如，2021 年的研究解释说，咖啡因通过阻断大脑化学物质腺苷（这是让你感到疲劳的原因）来提高警觉性，同时触发肾上腺素的释放，肾上腺素被称为“战斗或逃跑”荷尔蒙。