Bed
Some form of covering blanket is often used to insulate the sleeper , often bed sheets , a quilt , or a duvet , collectively referred to as bedding . 
<triplet> blanket <subj> bedding <obj> subclass of <triplet> bed sheet <subj> bedding <obj> subclass of <triplet> duvet <subj> blanket <obj> subclass of <subj> bedding <obj> subclass of <triplet> bedding <subj> blanket <obj> has part