We had a low cost hollow fibre duvet, & due to my age, I was feeling boiling hot & then cold at night. I researched thoroughly what might be able to help, and wool duvets came up. I purchased one from the Wool Room, which had fantastic reviews, and am absolutely amazed at the difference it has made. My husband thought that I was going to force him to sleep under a duvet that was going to make him feel cold. Anyway, we are both toasty warm with our different temperature requirements!