The Reason Coffee Makes Some People Sleepy（英语阅读）（每日一摸）

The Reason Coffee Makes Some People Sleepy

The reason we get tired throughout the day is because a neurochemical called adenosine builds up and passes through receptors, which causes nerve cells to become less active and blood vessels in your brain to dilate. 翻译1

In short, your body gets the message that it’s time to rest. But since caffeine resembles adenosine, it binds to these receptors instead — blocking the actual adenosine from passing through and preventing your body from slowing down. 翻译2

“Just because our brain is no longer processing the adenosine doesn’t mean it stops producing it,” Michelle Worley, a registered nurse, told PureWow. “When the caffeine inevitably wears off, you’re left with an adenosine buildup which makes you feel even more tired.” 翻译3

It’s not unlike getting a burst of energy after eating something sugary, only to crash soon after. And speaking of sugar, if your go-to coffee concoction involves lots of it, that could contribute to post-coffee fatigue, too. 翻译4

There’s also the possibility that caffeine’s diuretic quality can cause dehydration, which can make you feel tired (though some studies have suggested that caffeine doesn’t dehydrate us nearly as much as we’ve been led to believe). 翻译5

Lastly, you may have built up such a high tolerance for caffeine that a cup of joe just doesn’t perk you up like it used to. 翻译6

相关词汇

receptor /rɪˈseptər/ n.受体；感受器；接受器
nerve /nɜːrv/ n.神经； nerve cell 神经细胞； nervous /ˈnɜːrvəs/ adj.神经的；紧张不安的
blood vessel 血管
dilate /daɪˈleɪt/ v.扩张；使扩张（英英：become wider）
resemble /rɪˈzembl/ vt.与…相似
registered nurse 注册护士； registered accountant 注册会计师；
evitable /ˈevətəbəl/ adj.可以避免的 inevitable /ɪnˈevɪtəbl/ adj.不可避免的 inevitably /ɪnˈevɪtəbli/ adv.不可避免地
wear off 逐渐消失；逐渐减少
only to 却；然而
soon after 不久之后
speaking of ... , ... 谈到…, …
concoction /kənˈkɑːkʃn/ n.混合物（英英：any foodstuff made by combining different ingredients）
fatigue /fəˈtiːɡ/ n.乏力（英英：temporary loss of strength and energy resulting from hard physical or mental work）
diuretic /ˌdaɪjuˈretɪk/ adj.利尿的；n.利尿剂
dehydration /ˌdiːhaɪˈdreɪʃn/ n.脱水 dehydrate /diːˈhaɪdreɪt/ vt.使脱水
Lastly 最终
tolerance /ˈtɑːlərəns/ n.耐受程度
a cup of joe 一杯咖啡（俚语）
perk sb up 让某人振作起来