If your woken from deep sleep but can go back into a light sleep, you will find it easier to wake from a light sleep.

如果你从深度睡眠中醒来了，但可以重新回到轻度睡眠中，你会发现从轻度睡眠中醒来更容易。

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This beautiful room is bathed in light. You'll wake up every morning in a good humor.

这个漂亮的房间沐浴着阳光，每天早上醒来时你就会有个好心情。

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Lack of light may upset your sleep-wake cycle and other circadian rhythms. And it may cause problems with a brain chemical called serotonin that affects mood.

缺乏光照有可能破坏你的醒睡周期和昼夜节律，还可能改变一种叫血清素的脑化学物质进而影响情绪。

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In another experiment the researchers wake up sleeping mice by sending a light signal to the hypothalamus, the brain's controller of sleep-wake cycles.

FORBES: Magazine Article

When a neutrino interacts in the NOvA detector , the particles it produces leave trails of light in their wake.

ENGADGET: NOvA neutrino detector captures cosmic rays in 3D, aims to unlock the mysteries of the universe

"It doesn't matter if you're asleep or whatever, you'll wake up and you'll see that red light, and you'll look at it, " Taylor says of his BlackBerry.

CNN: Why we can't unplug on vacation