从18世纪和19世纪的日记和其他个人记录中，睡眠科学家已经得出结论——人的平均睡眠时间约为每晚9.5小时。
From diary entries and other personal accounts from the 18th and 19th centuries, sleep scientists have reached the conclusion—that the average person used to sleep about 9.5 hours a night.
睡眠科学有时模糊而令人迷惑。
科学家们已经发现了非同寻常的新证据，证明睡眠时我们的身体如何自行恢复。
Scientists have discovered remarkable new evidence showing how the body rebuilds itself while we sleep.
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