一项研究或许可以给出解释：这些新的小生命接触日光的多少决定了身体中控制生理时钟的基因的特性。

One study may help explain why: the amount of daylight to which newborn mice are exposed sets the behavior of key biological clock genes for life.

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为了发现肾上腺钟是如何控制的，研究者在不同的时间处理了小鼠和时钟基因缺失的小鼠的肾上腺切片。

To find out how the adrenal clock ticks, the researchers first treated slices of adrenal tissue from normal mice and mice lacking critical clock genes at different time points.

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