Weighted blankets - brilliant or waste of money?

There hasn’t been a post on these since Feb18 so thought I’d ask. Does anyone have experience with them? Do they help aid sleep or would it feel scary to be trapped underneath one? I’m asking for my father. Thanks so much

My daughter bought one of the more expensive “best” ones 6 months ago & has barely used it, not at all for months. Seems to be a clever marketing ploy imho.