Your body needs to experience all three steps of sleep—light sleep, dream, and deep sleep—to fully repair itself.

你的身体需要经历睡眠的三个步骤——浅睡眠、做梦和深睡眠——从而进行完全的自我修复。

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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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Also, the amount of light sleep increases with age, and the amount of deep sleep is reduced.

同样，轻度睡眠也随着年龄的增加而增加，深度睡眠则相反。

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So much light in the sky would not let his daughter sleep.

VOA: special.2009.03.28

It then waits till you fall asleep then starts the timer, waiting for you to get roughly 26.5 minutes of shuteye, before rousing you during a light sleep cycle.

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Instead of making a loud noise at a predetermined time, the Smart Alarm gently vibrates when you're in a light sleep, somewhere around the time you'd like to wake up (up to 30 minutes before you've actually set it).

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Light and quality of sleep are well-known to be linked, as anyone who has ever pulled a night shift will attest.

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