Weighted blankets - a newer concept to me. Experiences with, please. [View all]

[No Vested Interest]

I'm good with the idea of enabling better sleep.

Apparently weighted blankets are supposed to be good for this - calming, easing anxiety, etc.
They come in various weights, which may have to do with one's own weight and size.
What is the base fabric, and does it make a difference, other than the obvious - cleaning/washing the blanket?
Brands?

I am old, with middle-aged adult children.
Am thinking of gifting them, or some of them, with such for Christmas, if they seem worthwhile.