When Sarah Jay had her first seizure, she was in her mid-20s and working a high-stress job at a call center in Springfield, Mo.

"I was going to go on break," she says. "I was heading towards the bathroom and then I fell and passed out."

An ambulance took Jay to the hospital but doctors there couldn't find anything wrong. Jay figured it was a one-time thing. Then a week later, she had another seizure. And that kept happening once or twice a week.

"So I was put on short-term disability for my work to try to figure out what was going on," says Jay, who's now 29.

The most likely cause for her seizures was abnormal electrical activity in her brain. In other words, epilepsy.

But Jay's doctors wanted to be sure. In May 2013, they admitted her to a hospital epilepsy center, put electrodes on her scalp and began watching her brain activity.

An epileptic seizure looks a bit like an electrical storm in the brain. Neurons begin to fire uncontrollably, which can cause patients to lose consciousness or have muscle spasms.

But during Jay's seizures, her brain activity appeared completely normal.

"It was kind of surreal," she says. "This woman, she sat me down and she was like, 'OK, you do not have epilepsy.' And I'm like, 'OK, so what's going on?' "

The woman told Jay her seizures were the result of a psychological disorder called psychogenic non-epileptic seizures.

PNES is a surprisingly common disorder, says John Stern, who directs the epilepsy clinical program at the University of California, Los Angeles. About 1 in 3 people who come to UCLA for uncontrolled seizures don't have epilepsy. Usually, they have PNES, he says.

That's not something most patients want to hear, Stern says, especially if they've already been diagnosed with epilepsy somewhere else.

"The person's being told that all the doctors who said this is epilepsy are wrong, and there's a condition now that I have which I've never heard of," he says. "That's disarming. That's confusing."

Sometimes patients simply reject the new diagnosis and that response is unfortunate, Stern says, because epilepsy drugs don't help people with PNES. In fact, as a neurologist, he has no way to treat these patients.

So he typically refers them to his colleague, Patricia Walshaw, a psychologist who directs the neurobehavioral epilepsy program at UCLA.

"They may feel lost or confused. They may be angry. There's denial that arises," Walshaw says. "That's where I pick up."

Many people with PNES face stigma and skepticism about their condition, even from their friends and family, so they need support.

"The common misconception is that the seizures are all in the person's head, or that they're just making it up, or that nothing is wrong," Walshaw says. "But that couldn't really be farther from the truth."

PNES patients are not faking their seizures. The events look and feel a lot like epileptic seizures and can be just as debilitating. For example, like people with uncontrolled epilepsy, people with PNES can't get a driver's license.

What Jay and most PNES patients want to know is: If an electrical problem isn't causing their seizures, what is?

The answer is complicated. PNES is more common among young women and people with depression or some other mental illness. And often, Warshaw says, the seizures are a reaction to some sort of traumatic experience like abuse.

"And you need to have a treatment that really focuses on trauma," Warshaw says.

Sometimes the seizures stop once patients learn they don't have epilepsy. But usually, Warshaw says, PNES requires years of therapy and mental health treatment.

Jay says she doesn't have a history of abuse but has been hospitalized for severe depression. So she is now receiving treatment for both PNES and depression.

It's helping, but her seizures do still happen and it can be difficult to explain to people that she does not have epilepsy.

"Going to the ER can be kind of hurtful because they don't know what you're talking about all the time." Jay says sometimes doctors and nurses think she's faking it.

But she's lucky in many ways. She says that her family and friends have been very supportive and she's found a community of other PNES patients through online support groups.

Copyright 2018 NPR. To see more, visit http://www.npr.org/.