If you listen to right-wing media and Donald Trump, Hillary Clinton is sick. Far too sick to be president.

She might be suffering from a language disorder called dysphasia, according to non-medical expert and Trump talking head Katrina Pierson. Or maybe it’s seizures ― at least Fox News host Sean Hannity thinks so. The Drudge Report is concerned about her coughing. Online sleuths note she’s been using an awful lot of pillows. Rudy Giuliani thinks it’s “bizarre” that she had to pee during a debate, and urged the public to Google “Hillary Clinton illness” to learn the truth.

Trump, who’s never met a conspiracy theory he doesn’t like, has insinuated that Clinton isn’t well. He declared that Clinton lacks the “mental and physical stamina” to take on ISIS. He’s characterized her as “unstable,” “unbalanced” and “totally unhinged.”

“Honestly, I don’t think she’s all there,” Trump said.

It’s hard to hear the words “unstable” and “unbalanced” and not wonder if he’s referring to her hormones. The subtext of the rumors spouted by Trump and his crew of armchair doctors is clear: Clinton is biologically unfit to lead. She’s a woman, after all.

Forty-six years ago, Edgar Berman, a retired physician and Hubert Humphrey’s close confidant, declared that women were temperamentally unsuited to hold high office because of their “raging hormonal imbalance.”

“Suppose that we had a menopausal woman president who had to make the decision of the Bay of the Pigs?” he pondered. “All things being equal, I would still rather have had a male JFK make the Cuban Missile Crisis decisions than a female of similar age.”

In 2016, it’s no longer considered acceptable for public figures to opine about how women’s menstrual cycles, or lack of them, disqualify them from high-ranking jobs. But that doesn’t mean those opinions aren’t held in private.

At the heart of many conspiracy theories is some sort of human prejudice, said Mark Fenster, a law professor at the University of Florida and the author of Conspiracy Theories: Secrecy and Power in American Culture.

He pointed to the implicit racial motivation behind “birtherism,” a conspiracy movement that alleges President Barack Obama was not born in the U.S. and is thus ineligible to be president. Trump is a prominent peddler of this claim. 

“It was never just that he was a child of immigrants who was born elsewhere,” he said. “It was always that he was born in a Muslim country to a Muslim father. It was very specific as to what it was he represented.”

Gender bias “absolutely” plays a role in the conspiracy theories around Clinton’s health, even if it’s not the primary motivating factor, Fenster said. 

“Every part of his critique of her has a gender component to it,” he said. “I think that’s true with the health conspiracies. It’s very much mocking her as an ‘old lady.’”

Stephanie Shields, a professor at Pennsylvania State University who studies gender and emotion, said it’s not uncommon for women aspiring to positions of power to be criticized as “unstable” or “emotional” as a way of monitoring who has a right to a voice.

“Calling someone emotional is a way to police their behavior, label them as irrational, and label them as not really having a legitimate basis for speaking,” she said.

The focus on Clinton’s health, she said, also “goes back to always turning women into their bodies.”

Stretching as far back as 1900 BC, women’s reproductive systems have been associated with irrational emotions. The term “hysteria” actually comes from the Greek word for uterus.

HuffPost reporter Catherine Pearson explains:

Hysteria was the first mental disorder attributed to women (and only women) — a catch-all for symptoms including, but by no means limited to: nervousness, hallucinations, emotional outbursts and various urges of the sexual variety...

Egyptian texts dating as far back as 1900 BC argued that hysterical disorders were caused by women’s wombs moving throughout their bodies. The ancient Greeks believed it, too. In the 5th century BC, Hippocrates (i.e., the founder of western medicine, in what may not go down as his greatest achievement) first coined the term “hysteria” — from “hystera,” or uterus — and also attributed its cause to abnormal movements of the womb in a woman’s body.

It’s easy to laugh-off female hysteria as preposterous and antiquated pseudo-science, but the fact is, the American Psychiatric Association didn’t drop the term until the early 1950s. And though it had taken on a very different meaning from its early roots, “hysterical neurosis” didn’t disappear from the DSM — often referred to as the bible of modern psychiatry — until 1980.

To Dianne Bystrom, the director of the Carrie Chapman Catt Center for Women and Politics at Iowa State University, the attacks on Clinton’s physical and mental health remind her of the arguments men used in the early 1900s to justify why women shouldn’t have the right to vote. 

“It is interesting as I sit here reflecting on suffrage today,” she said, highlighting that Friday is Women’s Equality Day. “The arguments are the same. Women are the frail sex, the ones that don’t quite have the stamina to be involved in the ugly game of politics.”

She said the gender bias by the Trump campaign towards Clinton is more extreme than she can remember in recent history, calling his tactics “vicious.” 

“In my years of studying male versus female rhetoric in politics races, I haven’t seen anyone go this far as to attack a woman for her health when there seems to be no founded reason for it,” she said. 

Let’s get real: The wild conspiracy theories around Clinton’s health are a convenient way to mask misogyny inside “legitimate” medical concerns. Her critics can’t call her crazy, so instead they use stand-ins like “unbalanced” and lacking “mental stamina.”

Trump has a long history of gendered attacks on Clinton. He has said she doesn’t “look” presidential. He doesn’t like her voice. He even made a callous joke about someone shooting her. 

Now, he’s arguing that she’s not physically or mentally up for the job. That’s sexism, plain and simple.