There are three main ways that animals survive the cold in winter: sleep, adapt or migrate.

动物在寒冷的冬天有三种主要的生存方式：休眠、适应或迁徙。

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It was too cold for them to sleep much.

VOA: special.2009.07.22

At night, it was too cold to sleep.

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In fact, I would play long into the night to keep from having to climb into a bed that was so cold I couldn't sleep.

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"Probably the restriction of movements by clothing could increase the length of sleep, and a cold environment makes swaddling possible without overheating, " she says.

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