Take a few deep breaths, relax, and your body will assume that it's time to sleep and you'll be drooling on your pillow in no time.

做几下深呼吸，然后全身放松，你的身体会认为睡觉的时候到了，于你就能迅速坠入梦乡。

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In a nutshell, if you sleep for eight hours a night go to work and find yourself lolling and drooling on the keyboard, you aren't getting enough.

BBC: NEWS | UK | Magazine | Why should we have eight hours' sleep?