I bought a wool duvet and a wool mattress topper to help with my heat in the night. I love them.
BUT the thing that made the most difference to hot sweats in the night was a long-sleeved merino top. Utterly amazing. They wick away sweat, don't smell, and keep you dry. Mine weren't cheap but worth every penny and I washed them again and again and they were as good as new. Don't wear them now as HRT has stopped the night sweats (thank god), but still love my wool duvet.