Scroll through Amazon's seemingly endless list of fidget spinners, and you'll see that the vast majority of these toys promise to relieve stress, reduce anxiety, and treat ADD, ADHD, and even autism.

If you haven't played with one yet, fidget spinners are small plastic and metal toys made with skate bearings. You flick them, and they spin for a very long time (usually longer than a minute). They are, admittedly, lots of fun to spin and stare at, and they're everywhere.

The toy everyone is talking about may be fun and a cool physics trick, but there's no evidence it has any actual medical benefits. But rather than selling these purely as a fun toy, most of them are being sold as being "perfect for ADD, ADHD, anxiety, and autism" or somesuch. Click further, and even more promises are made: "Ideal for people trying to quite nail biting, smoking, leg shaking and all type of attention disorder issues … Great Toy For Fidgeters, Anxiety, Focusing, ADHD, Autism, Quitting Bad Habits, Staying Awake."

Very little fidgeting is actually needed to use a fidget spinner

There is at least some evidence that foot tapping, squirming, "hyperactivity," and other types of "excess gross motor activity" may be a "compensatory mechanism that facilitates neurocognitive functioning in children with ADHD," according to a 2015 study published in The Journal of Abnormal Child Psychology. That study's lead author, Mark Rapport, head of the Children's Learning Clinic at the University of Central Florida, found some evidence that adults should "avoid overcorrecting gross motor activity [of children with ADHD] during academic tasks."

In other words, there is loose evidence that fidgeting while performing a task may help some children learn.

The thing is, very little fidgeting is actually needed to use a fidget spinner, and fidget spinners are a secondary distraction whereas tapping your feet is something you can easily do while performing another activity.

"Fidget spinners may prove to be more of a distraction than a help because the toy moves rather than the child," Rapport told me. "It is the child's movement that helps them maintain the necessary level of arousal needed to complete cognitively demanding tasks."

That hasn't stopped companies, such as Addictive Fidget Toys, from advertising their spinners as providing a sense of comfort and peace in stressful situations. The company says that it makes the claim based on some anecdotal evidence.

"We have not done a scientific study ourselves, however we have several customers as well as some of our own staff that have told us it has helped them," said Addie, an employee at Addictive Fidget Toys.

"They are just a distraction. I would not recommend them to my patients."

Spinetic Spinners, another fidget toy company, told me there has been no fidget spinner-specific research done: "It is in our plan to seek out medical testing for our products to get a definite answer," the company said.

Therapists and behavioral psychologists aren't buying it, however. Julie Schweitzer, a professor at the University of California, Davis, who is a part of the Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, told the Boston Globe she doesn't consider the toys to be a "treatment" and has declined to support several fidget spinner companies who have reached out to her for an endorsement.

Maryland-based occupational therapist Stephen Poss said that the autistic children and those with ADHD he's worked with one-on-one haven't found fidget spinners to be therapeutic.

"I haven't seen any scientific evidence on fidget spinners," Poss told me. "From what I've observed, they are just a distraction. I would not recommend them to my patients."

Maybe there's a reason, then, why schools around the country are starting to ban them.