当你晚上住在一个新的环境里，比如酒店或朋友家里时，通常情况下这一晚总是会觉得睡得不好，其实这就是初夜效应。有研究人员在观察志愿者睡眠时发现，大脑的图像进入到一个新环境中，第一晚时的大脑其实只有半边进入了深度睡眠，而另一半没有，特别是左半球更容易被唤醒。学者推测这是遗留下来的进化生存机制，让我们在陌生的环境保持警惕，在一些动物身上，也证实了只用一半大脑睡觉的半睡眠，不过，人只会在第一晚，之后就会睡得很香了。
When you live in a new environment at night, such as hotels or friends' homes, you usually feel that you don't sleep well at this night. In fact, this is the early night effect. Some researchers found that volunteers' sleep found that the image of the brain entered a new environment. In the first night, the brain actually only entered deep sleep, and the other half did not, especially the left hemisphere is easier to be awakened. Scholars speculate that this is the evolutionary survival mechanism leftover, allowing us to be vigilant in a strange environment. In some animals, it also confirms that only half of the brain sleeps half of sleep. Sleep very fragrant.