"Then she drank a pint of water with two Rohypnol and stumbled to her bed and pulled the duvet over her head." (253)

What is a Duvet?

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In the United States, a Duvet is the same as a comforter, in that it is a blanket filled with feathers and acts as a thermal insulator. Usually, they are covered with a closable cover however, simiar to a pillow case with a zipper. 
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However, in Sweden, and all of Scandinavia, what they call a comforter is filled with synthetic fiber filler, quilted and stitched together in place to keep it evenly distributed. Its main purpose to sit on top of the rest of the bedding to give it a layered look.