By Riley Beggin,

Last October, Matt Herich was listening to the news while he drove door to door delivering pizzas. A story came on the radio about a technology that sends an electric current through your brain to possibly make you better at some things — moving, remembering, learning. He was fascinated.

The neurotechnology is called transcranial direct current stimulation, or tDCS for short. At its simplest, the method involves a device that uses little more than a 9-volt battery and some electrodes to send a low-intensity electrical current to a targeted area of the brain, typically via a headset.

More than a 1,000 studies have been published in peer-reviewed journals over the last decade suggesting benefits of the technique — maybe regulating mood, possibly improving language skills — but its effects, good or bad, are far from clear.

Although researchers see possibilities for tDCS in treating diseases and boosting performance, it’s still an exploratory technology, says Mark George, editor-in-chief of Brain Stimulation, a leading journal on neuromodulation. And leading experts have warned against at-home use of such devices.

“If we can figure out safe long-term applications, it’s so inexpensive we might be able to use it to boost tons of things,” says George, a professor at the Medical University of South Carolina. “But I have to underline might — we don’t know yet.”

When Herich finished his shift delivering pizzas, he raced home and began googling. He found a thriving community on Reddit and other online forums dedicated to discussing ways to self-administer tDCS.

After reading some scientific studies on neurostimulation, Herich decided to give it a try. He eventually got his hands on a rudimentary tDCS device made by a student at Northern Arizona University.

“I did my research before I put the device on my head,” Herich says. “So it was a mix between me being confident it would be safe and me taking a leap of faith.”

In his opinion, the leap of faith paid off. Herich takes online courses on machine learning, and he says that one 20-minute session of tDCS puts him in a state of intense focus that increases his productivity and helps him learn abstract math much faster than before.

Herich is not alone — beyond the DIY neurostimulation community, companies are cashing in on the phenomenon, offering brain stimulation kits and ready-to-wear headsets, like Thync and Halo. While the simplest devices can be made with items found in a hardware store, the best-selling versions like ActivaDose or the can cost more than $300.

And sales of the devices spike at fairly regular times, says Robin Azzam, CEO of a leading tDCS retailer Caputron: around college midterms and finals. Caputron also helps point customers to academic studies about tDCS. And Azzam says articles on cognitive enhancement are in particularly high demand during exam times.

George says he’s also heard students are using tDCS to study for exams, but he doesn’t recommend it: There isn’t enough data to back up claims that it is effective or safe.

He says an updated article will be published soon detailing the experts’ concerns about liberal use of tDCS by the DIY community. The main worries include the risks of mistakes in administration by amateurs and the uncertainty of long-term harmful effects of the technique.

Besides, George says, at-home users that attempt to study with the device may actually be doing themselves a disservice.

“When we learn something, we’re more likely to remember it in the same environment as when we learned it,” he says. “So if you study with one of these devices on and then you take your test without the device, you’ve violated that rule. You may be very good with it on, but unless they allow you to do that in the exam you’re actually hurting yourself.”

Plus, the safety of devices can vary — given that most tDCS devices aren’t marketed with specific medical claims, they are not reviewed by the Food and Drug Administration.

“A lot of the people that buy these think that they’re safe because a company is allowed to sell them,” says Vince Clark, director of the Psychology Clinical Neuroscience Center at the University of New Mexico. “What they don’t know is that a lot of those devices are never evaluated by the FDA. They go to market without safety studies that everybody expects must have happened. They haven’t.”

But like Herich, many users read the literature that supports and condemns tDCS use outside of clinical settings and choose to move forward anyway. And according to one academic review of the do-it-yourself brain stimulation community, most DIYers do draw heavily on existing scientific knowledge, circulate academic journal articles and adopt the standard electrode placement used by scientists.

“I do understand the risks,” Herich says. “I know … the nature of what it is that I’m doing, connecting a 9-volt to the forehead.” He acknowledges that to many people it may sound crazy. “I don’t know,” he says, “I think I just accept that risk.”