Early in her time as a medical student in the late 1950s, Paula J. Clayton watched a psychiatrist analyze a patient with clinical depression.

The doctor, who had herself been analyzed by both Carl Jung and Sigmund Freud and now taught at Washington University in St. Louis, asked the patient to explain his dreams, and the two spent time discussing what they meant.

But when the session was over, the doctor did something that Freud would never have done: She prescribed electroshock therapy.

It was something of a revelation for Dr. Clayton: The old methods of psychiatry, steeped in Freudian theory, had their limits, and physiological treatments were needed too. She came to believe that a new approach was necessary, beyond analysis’s reliance on talk therapy, one based not in philosophy and speculation but in empirical research and data and a conviction that mental illness, like any illness, can be diagnosed and treated.

She was at the right place at the right time. Dr. Clayton was part of a generation of clinical psychiatrists who, in the decades after World War II, revolutionized their field by applying medical rigor to the diagnosis of mental illness. And nowhere was this revolution more apparent than at Washington University. Her mentor, George Winokur, drilled into his students the commandment “Data Shall Be Your God.”

Dr. Clayton joined the Washington University medical faculty in 1965, and in 1969 she and Dr. Winokur, along with their colleague Dr. Theodore Reich, published “Manic Depressive Illness,” one of the first books to study manic depression through a rigorous, outcome-based approach.

“She was a very careful empirical researcher at a time when empirical research did not hold much sway,” Richard Friedman, a psychiatrist at Weill Cornell Medical College in New York, said in an interview.

Dr. Clayton and her co-authors found, for example, that manic depression was most likely hereditary, that it affected men and women differently, and that it had a high morbidity rate — that is, many patients, left untreated, died by suicide.

The “untreated” part is important, because Dr. Clayton went on to become one of the leading voices for destigmatizing depression and suicide in America.

She moved beyond the academy to become something of a public figure, adept at translating the latest research on mental illness for a broad audience at a time when issues like mania and suicide were still shrouded in mystery and myth.

Dr. Clayton died on Sept. 4 in Pasadena, Calif., at 86. Her daughter, Clarissa Weirick, said the cause was complications of a non-Covid viral infection.

First as a professor at the University of Minnesota — where she was the first woman to chair a psychiatry department in the country — and later as the medical director at the American Foundation for Suicide Prevention, Dr. Clayton worked tirelessly to show the public what medical researchers already knew: that suicide almost always resulted from an underlying mental illness.

“When you’re feeling sick from cancer or heart disease, you certainly call your doctor first, and yet with suicide” you don’t think of treatment as a solution, she said in a 2007 interview with a reporter for McClatchy. “I think it’s just that they don’t recognize it as a serious illness.”

Dr. Clayton reveled in the role of mythbuster. Suicides do not peak around the holidays, she told reporters, audiences and congressional hearings — April and May see the highest numbers. Women attempt suicide twice as often as men, but men are four times as successful.

“She was a pioneer and a force in suicide prevention in part because she believed people should know and understand that suicide can be prevented,” Dr. Jill Harkavy-Friedman, the vice president for research at the American Foundation for Suicide Prevention, said in an interview. “That didn’t happen before. People ran away from the topic.”

Paula Jean Limberg was born on Dec. 1, 1934, in St. Louis. Her father, Oscar Limberg, worked for a clothing company. Her mother, Dorothea (Pflasterer) Limberg, was active in the women’s suffrage movement, something Dr. Clayton later cited as an inspiration for her own career.

Her marriage to Charles Clayton ended in divorce. In addition to her daughter, she is survived by her sons, Matthew and Andrew, and seven grandchildren.

Dr. Clayton studied pre-med at the University of Michigan, graduating in 1956, and enrolled in medical school at Washington University, graduating in 1960. After joining the university’s faculty, she moved to the University of Minnesota in 1980.

Her work around bipolar disorder was especially groundbreaking. Though its broad contours were well understood, it was still seen as a mystery even by many psychiatrists. And too many people still saw manic outbursts of energy in somewhat romantic terms, as a seedbed for great art and ideas.

“There was a bit of glamour attached to bipolar disorder, which was wholly inaccurate — there’s no glamour to that disease,” John Greden, a psychiatrist at the University of Michigan and the founder of the Eisenberg Family Depression Center, said in an interview.

Dr. Clayton helped show that bipolar disorder and unipolar depression were two ends of a spectrum, a view that has led to breakthroughs in the diagnosis and treatment of both conditions.

She also demonstrated that while bereavement and grief can trigger major depression, periods of grief, even lasting a year, were not in themselves depressive episodes. And she showed that grief, far from progressing along a neatly described five-stage process, was personal and idiosyncratic — an insight that changed the way doctors and the public understand how people deal with loss.

Dr. Clayton stepped down as chairwoman at Minnesota in 1999, and after moving to Santa Fe, N.M., began teaching part time at the University of New Mexico.

Just six years later, though, a recruiter contacted her: The American Foundation for Suicide Prevention needed a medical director, someone who could take the work of its network of researchers to the general public.

Dr. Clayton jumped at the chance, leaving her life of semiretirement in New Mexico for New York. She created films for schools and parents, and she became a constant presence at government hearings, from Congress to City Councils.

She was especially vocal about suicide among Native Americans and members of the military and veterans, the rates of which spiked after the invasions of Afghanistan and Iraq. She urged insurance companies to improve mental health coverage. And even after she retired in 2015, she continued to write and speak, convinced that with enough public education, the country could start to lower its tragically high suicide rates.

“Before her, people talked about suicide like it was this mystical, horrifying behavior,” Dr. Friedman said. “Her work destigmatized depression, and because of that, so many people owe their lives to her.”

If you are having thoughts of suicide, call the National Suicide Prevention Lifeline at 1-800-273-8255 (TALK). You can find a list of additional resources at SpeakingOfSuicide.com/resources.