“Bill Dement was an evangelist about sleep,” Dr. Rafael Pelayo, a Stanford psychiatry professor who succeeded Dr. Dement in leading the sleep class, said in a phone interview. “He felt that not enough people knew about sleep disorders, and he thought of his students as multipliers who would tell the world about them.”
Dr. Dement’s expertise led to his appointment as chairman of a federal commission on sleep disorders. The commission reported in 1992 that 40 million Americans had undiagnosed, untreated, mistreated or chronic sleep problems — findings that led Congress to establish the National Center on Sleep Disorders Research, within the National Institutes of Health, in 1993.
When Dr. Dement testified on Capitol Hill five years later about the sleep center’s progress, he said he was pleased with its research but disappointed that the government had not sounded loud enough alarms about the serious, sometimes fatal, consequences of unhealthful sleep.
“The lack of awareness is so pervasive that victims don’t know what is wrong with them, and doctors don’t ask,” he told the House Health and Energy Subcommittee. “There are no mechanisms in place to disseminate the messages, no large organizations, no masses of enlightened victims, no faculty positions, no way to break into the medical school curriculum.”
Dr. Dement was widely referred to as the “father of sleep medicine.”
William Charles Dement was born on July 29, 1928, in Wenatchee, Wash., in the north-central part of the state, and grew up further south in Walla Walla. His father, Charles, was a tax agent and bookkeeper, and his mother, Kathryn (Severyns) Dement, was a homemaker.
After serving in the Army in postwar Japan, where he edited a regiment newspaper, he earned a bachelor’s degree in basic medical science at the University of Washington, Seattle, in 1951. He paid his way by working as a jazz bassist and hosted jam sessions on his houseboat.
Dr. Dement’s fascination with sleep began in medical school at the University of Chicago. He became intrigued with the work of Nathaniel Kleitman, a physiologist who was credited with doing pioneering research on sleep when the field barely existed. Dr. Kleitman and a graduate student, Eugene Aserinsky, first reported the discovery of rapid eye movement, or REM, during sleep.
Dr. Dement’s fascination with sleep swelled when Mr. Aserinsky told him what the flickering eye movements meant.
“‘Dr. Kleitman and I think these movements might be related to dreaming,’” Dr. Dement recalled Mr. Aserinsky telling him. “For a student interested in psychiatry, this offhand comment was more stunning than if he had just offered me a winning lottery ticket.”
After joining Dr. Kleitman’s sleep laboratory, Dr. Dement filmed subjects in REM sleep — one subject, who was studying at the university, was the future writer, director and actress Elaine May — and studied the connection between REM sleep and dreams.
In measuring the brain waves and eye movements of nine sleeping subjects in 1956, Dr. Dement and Dr. Kleitman found a high incidence of dream recall when subjects were awakened five to 15 minutes after REM sleep had begun.
The rapid eye movements “represented the visual imagery of the dream” — in other words, “they corresponded to where and at what the dreamer was looking” — the two scientists reported in a paper published the next year in the Journal of Experimental Psychology.
Dr. Dement, who had received his medical degree in 1955, earned a Ph.D. in neurophysiology, also at the University of Chicago, two years later. He moved to Manhattan for his medical internship at Mount Sinai Hospital and opened a sleep lab in his apartment. He used himself as a subject for his research, as well as several Radio City Rockettes.
Dr. Dement moved to Stanford in 1963. There he studied insomnia and narcolepsy in volunteers and in 1970 opened a sleep clinic with a colleague, Dr. Christian Guilleminault (who died last year), developing increasingly sophisticated ways to measure sleep.
“It became more and more obvious that there were a lot of abnormal sleep problems, more than anyone suspected,” Dr. Dement said in a video interview for Stanford in 2016.
One focus of their research was sleep apnea, in which people often stop breathing while asleep. The condition is connected to illnesses like Type 2 diabetes and high blood pressure. (Dr. Dement himself was given a diagnosis of sleep apnea about three years before his death.)
Dr. Emmanuel Mignot, a professor of sleep medicine at Stanford, recalled Dr. Dement telling him in the late 1980s that he was about to present research showing that sleep apnea affected as much as 20 percent of the population.
“At the time, most thought it affected more like 2 percent,” Dr. Mignot was quoted as saying in a Stanford obituary about Dr. Dement. “I said, ‘Don’t say this. People will think you’re crazy. You’ll appear as a lunatic.’ He did sometimes appear like a lunatic. But the problem is, he was right.”
Dr. Dement was the founding president of the Association of Sleep Disorder Centers (now the American Academy of Sleep Medicine) and helped start the Sleep Research Society and the journal Sleep. He wrote several books, including “The Promise of Sleep” (1999) and “The Stanford Sleep Book” (2006), which was rewritten with Dr. Pelayo and reissued in 2017 as “Dement’s Sleep & Dreams.”
“I’ve stalked the sleeping self to understand what happens when we sleep,” he wrote in “The Promise of Sleep.” “Night after night, I’ve watched people in our lab and our clinic undergo the commonplace and profound transformation called falling asleep.”
In addition to his son, Dr. Dement is survived by two daughters, Catherine Roos and Elizabeth Dement, and six grandchildren. His wife, Eleanor (Weber) Dement, died in 2014.
Dr. Dement slept well for most of his life, Ms. Roos said in email, going to bed early and rising by 5 a.m. to work without interruption. Several years ago, when he was 84, he described one technique to put himself to sleep: watching something that is not too distracting, like back-to-back reruns of the sitcom “Everybody Loves Raymond.”
“I guess reading things you’ve already read and watching things you’ve already seen probably helps put you to sleep,” he told The New York Times.
But, he added, “I haven’t actually done a study on that.”