Wiggle chairs are seats designed to encourage a child to wiggle on them. They sometimes require balancing on something or regular fidgeting to keep upright. Supposedly this helps a child to focus by giving them an outlet for fidgeting that doesn't interfere with their ability to learn. Apparently some elementary schools are providing them for students with the belief it will help them to learn.
I've seen claims both that it helps all children to learn, and claims that these chairs are specifically useful to children with ADHD or autism. However, I've found no real studies to back up the claims, and most of the claims online seem to be by furniture selling sites that have a clear conflict of interest when it comes to claiming these chairs will help kids to learn.
Have there been any proper studies on wiggle chairs, and if so have they been proven effective in assisting young children with learning? I'm particularly interested in rather they have been proven to assist children with ADHD, but I'd be happy to have a study that focused on autism or neurotypical children as well.