organic lightweight duvet insert

...

Tencel™ is a branded material for Lyocell, a product of wood pulp found in certain trees — particularly fast-growing eucalyptus. This environmentally friendly material is wrinkle-resistant and is produced using a closed-loop process, so any waste created while making the material is recycled and reused. 
Soft, smooth, and hypoallergenic, Tencel™ is a great choice for eco-conscious consumers. However, keep in mind that it’s not quite as breathable as cotton or linen.

...

And finally, brushed cotton is for those looking for something in the middle in terms of cooling/heat-retaining qualities. To turn cotton into brushed cotton, the fabric undergoes a couple of extra treatments that result in the softest flannel-like bedlinen. While both percale and sateen sheets may take a few washes to become more supple and soft, a new set of brushed cotton bedding feels like you’ve slept in it forever. It is a great year-round option because it won’t warm or cool you down excessively.

...