Even caffeine, which is generally known only for its stimulatory effects, displays this property, depressing mouse locomotion at very low concentrations and stimulating it at higher ones.

就连人们通常觉得有刺激作用的咖啡因，也表现出了这种特性，它在浓度极低的情况下会抑制老鼠的运动，而在浓度较高的情况下则会刺激老鼠。

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Dr. Mary K. Townsend, one of the researchers on the work, said: 'We only observed an increased risk of urinary incontinence among women with the highest intakes of caffeine.'

这项工作的一个研究人员Mary K. Townsend博士称：“我们只观察那些高咖啡因摄入量的女性增加患尿失禁的风险。”

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Most people are not aware that caffeine has a half life of up to eight hours and can affect not only your ability to fall asleep, but also the quality of sleep you are getting.

大多数人都不知道，咖啡因有一个长达八小时的半衰期，不仅会影响你的入睡能力，而且还会影响你的睡眠质量。

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The directions also advise people to limit caffeine products and to drink only half the bottle if they want a moderate amount of energy.

VOA: special.2009.07.22

There, the only defense against your own caffeine-amped angst is your sense of humor and the just-as-crazy team (you got to be, right?) working diligently alongside you.

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But the benefit was only half as big as that for caffeine.

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To date, caffeine has been approved for use only in soft drinks, and only at concentrations under 200 parts per million.

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