For three weeks, the participants lay in bed with their heads tipped down at a 6 percent tilt.

三周时间里，参与者保持头部6度向下倾斜躺在床上。

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For three weeks, the participants lay in bed with their heads tipped down at a 6 percent tilt.

三周时间里，参与者保持头部6度向下倾斜躺在床上。

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