Close watchers of “The Watcher,” the popular Netflix series about a couple who move to the New Jersey suburbs, only to be stalked in their dream home, may have caught the reference.

It comes when one of the main characters, played by Bobby Cannavale, stumbles upon a creepy man in his kitchen who describes himself as a building inspector. After Mr. Cannavale’s character remarks that people are fleeing New York City, the man replies: “It’s the fourth turning.”

The puzzlement on Mr. Cannavale’s face invites an explanation.

According to “fourth turning” proponents, American history goes through recurring cycles. Each one, which lasts about 80 to 100 years, consists of four generation-long seasons, or “turnings.” The winter season is a time of upheaval and reconstruction — a fourth turning.

The theory first appeared in “The Fourth Turning,” a work of pop political science that has had a cult following more or less since it was published in 1997. In the last few years of political turmoil, the book and its ideas have bubbled into the mainstream.

According to “The Fourth Turning,” previous crisis periods include the American Revolution, the Civil War and World War II. America entered its latest fourth turning in the mid-2000s. It will culminate in a crisis sometime in the 2020s — i.e., now.

One of the book’s authors, Neil Howe, 71, has become a frequent podcast guest. A follow-up, “The Fourth Turning Is Here,” comes out this month.

The theory is popular with people at both ends of the political spectrum. It also inspired an acclaimed Off Broadway play, “Heroes of the Fourth Turning,” which features a conservative Catholic writer, Teresa, who is obsessed with the book and its promise of a coming revolution.

The play’s author, Will Arbery, 33, said he heard about “The Fourth Turning” while researching Stephen K. Bannon, the right-wing firebrand and former adviser to President Donald J. Trump, who is a longtime fan of the book and directed a 2010 documentary based on its ideas. A writer for the HBO show “Succession,” Mr. Arbery said he had also found references to “The Fourth Turning” in modern corporate culture.

He described it as “this almost fun theory about history,” but added: “And yet there’s something deeply menacing about it.”

Mr. Arbery, who said he does not subscribe to the theory, sees parallels between the fourth turning and other nonscientific beliefs. “I modeled the way that Teresa talks about the fourth turning on the way that young liberals talk about astrology,” he said.

The book’s outlook on the near future has made it appealing to macro traders and crypto enthusiasts, and it is frequently cited on the podcasts “Macro Voices,” “Wealthion” and “On the Margin.”

“I’ve read ‘The Fourth Turning,’ and indeed found it useful from a macroeconomic investing perspective,” Lyn Alden, 35, an investment analyst, wrote in an email. “History doesn’t repeat, but it kind of gives us a loose framework to work with.”

For Ryen W. Thomas, 42, a filmmaker and co-host of a YouTube series, “Generational Talk,” “The Fourth Turning” captured a mood of decline in recent American life. “I remember feeling safe in the ’90s, and then as soon as 9/11 hit, the world went topsy-turvy,” he said. “Every time my cohort got to the point where we were optimistic, another crisis happened. When I read the book, I was like, ‘That makes sense.’”

“The Fourth Turning” was conceived during a period of relative calm. In the late 1980s, Mr. Howe, a Washington, D.C., policy analyst, teamed with William Strauss, a founder of the political satire troupe the Capitol Steps.

Their first book, “Generations,” told a story of American history through generational profiles going back to the 1600s. The book was said to have influenced Bill Clinton to choose a fellow baby boomer, Al Gore, as his running mate. Mr. Strauss died in 2007, and Mr. Howe has carried on the pair’s work since then.

When it was published, “The Fourth Turning” drew a withering review in The New York Times by the writer Michael Lind, who criticized the authors for cherry-picking facts and lumped them in with “purveyors of pseudoscience.” But when the 2008 financial crisis hit at almost exactly the point when the start of the fourth turning was predicted, it seemed to many that the authors might have been onto something. Recent events — the pandemic, the storming of the Capitol — have seemingly provided more evidence for the book’s fans.

Mr. Howe, who is the managing director of the demography team at the investment research firm Hedgeye, likened the popularity of “The Fourth Turning” to the stock of a staple business like Campbell Soup Company during an economic crisis. The worse the news gets, the more its fortunes rise.

“Obviously, it’s not intentional,” he said, speaking from his home in Virginia.

Historically, a fourth turning crisis has always translated into a civil war, a war of great nations, or both, according to the book. Either is possible over the next decade, Mr. Howe said. But he is a doomsayer with an optimistic streak: Each fourth turning, in his telling, kicks off a renaissance in civic life.

In the new book, he describes what a coming civil war or geopolitical conflict might look like — though he shies away from casting himself as a modern-day Nostradamus.

“This big tidal shift is arriving,” Mr. Howe said. “But if you’re asking me which wave is going to knock down the lighthouse, I can’t do that. I can just tell you that this is the time period. It gives you a good idea of what to watch for.”