No wonder these seats are called the nose bleeds.

The steep upper bowl of the Barclays Center has prompted at least four lawsuits from folks claiming they were crushed by fellow patrons who tumbled over the harrowingly sheer, narrow, dark rows or stairs.

“I just heard a ‘Watch out!’ and like a split second later, a pretty hefty guy landed on my back and on my neck,” said Kenneth Silver, 58, who was hit by a flying fan at a March hockey game.

Silver, who once had a regular seat in the upper level, said, “It’s almost like people are standing on top of each other. This is the most extreme arena I’ve seen in the New York area, and I’ve been in almost every one.”

His lawyer said the 19,000-seat Brooklyn venue’s “defective design” contributed to the incident.

The Manhattan man is just the latest to gripe about the Atlantic Avenue arena’s precipitous cheap seats.

In 2015, a boy at WWE’s Summer Slam was hit by a stumbling, “visibly intoxicated” patron who couldn’t navigate the stairs in Section 228, the child and his dad said in court papers.

In 2013, Long Islander Elizabeth Silver was at Billy Joel’s New Year’s Eve show when she fractured her wrist sitting in Section 211. An apparently drunken fan toppled into her, according to her lawsuit.

The problem was clear as soon as the arena opened in 2012 with a series of concerts by Jay-Z.

Sara Smith of Manhattan sued after breaking her wrist at one of those shows when the drunken lout behind her lost his footing and sent her flying.

She sought out security when the “rowdy” guy spilled beer on her hair, but after 15 minutes, no help arrived.

“He fell into me, and I flipped into the row in front of me. With force,” she said, according to a court transcript. “My face struck the railing. My legs were all bruised, and you know, everything hurt at this point, so I didn’t know what I had broken. I was just really scared.”

Fans around her started screaming, and her friend tried to scold the falling man, but he simply shrugged and climbed back into his own seat, court records said. It’s unclear if Barclays security made any effort to identify him.

Nearly 10 million people have gone to Barclays since it opened, said a spokesman who denied the arena has a falling-fan problem.

Smith and the boy’s family eventually settled their lawsuits for undisclosed sums. Elizabeth Silver’s case is pending, said lawyer Michael Castro, who said he’s gotten at least a dozen calls in less than two years from injured Barclays customers.

While inebriated fans are part of the problem, the steep incline of the upper bowl is also a factor in the frequent falls, as is the dense seating which leaves little room between rows for people to safely pass each other, the lawyer believes.

“I think you have a situation that’s already dangerous and now, you add in alcohol and it makes it exceedingly dangerous,” he said.

The steep nature of arenas is meant to bring fans who sit high closer to the action, architects and designers said.

“You don’t want to feel detached from the sport,” said Nader Tehrani, dean of Cooper Union’s Irwin S. Chanin School of Architecture. “You want the sweat to hit you.”

Some facilities, like opera houses and medical theaters, are intentionally steep to allow the audience the best view. Soccer stadiums in Europe and South America are “super steep,” Tehrani said, including the famed La Bombonera in Buenos Aires, where the upper deck has a vertigo-inducing 45-degree incline.

The upper bowl at Barclays Center sits at a 36-degree incline.

An arena spokesman called that “standard” for modern arenas, adding that at least nine other NBA arenas had a 36-degree pitch, and three others had 35-degree inclines.

Some experts disagreed.

Most sports venues in the United States typically have upper seating with an incline of 30 to 33 degrees, said James Renne of the Detroit-based firm Rossetti Architects, which designed Red Bull Arena in Harrison, NJ.

The recently “transformed” Madison Square Garden reshaped its upper bowl during a $1 billion, three-year renovation. It improved sightlines, put fans seven to 10 feet closer to the action, and made the area 17 percent steeper. But those changes still only brought the upper bowl’s pitch to about 30 degrees.

At Citifield, which opened in 2009, the upper-level incline is only 32degrees. Red Bull Arena, which opened in 2010, is 33 degrees. Data for Yankee and Metlife stadiums was not available.

Golden 1 Center in Sacramento, where two fans fell in the upper seats last year, has a slope of 34 degrees.

The higher the degree of incline, the steeper the stairs. There also is less legroom, and a feeling that getting to a seat is like walking a tightrope.

With little room to spare between rows, and cup holders which further block the space, fans in Barclays’ less-expensive seats struggle to walk past each other.

“Many fans are not comfortable with a steep bowl. You want more room when you go up higher,” Renne said. “There is a perception about the danger of falling.”

But there is no standard angle for upper-level seating, and building codes can allow for steep seating areas, he said.

Still, inclines of 34 degrees or more can start to feel “too steep,” Renne said. “It’s just not viable to sit in a seat in that kind of scenario or angle. There’s a threshold.”

It’s unclear how often fans fall because of the dicey designs, or if arenas and stadiums are required to keep track of the incidents.

“I’ve heard of people falling up there and people complaining it’s too steep,” said one Barclays worker who didn’t want to be named. “Most of the time when people fall, though, it’s because they’re intoxicated. I always tell people, ‘If you know someone with vertigo, don’t bring them up there.’”

Another worker added, “Even sober, I don’t even go past Row 15. It’s crazy up there.”

One Brooklyn Nets fan said she refuses to sit upstairs at the Barclays Center. “It makes me nervous,” she told The Post.

Kenneth Silver, who got hit at a New York Islanders game in March, was forced to leave the arena.

Barclays Center wouldn’t pick up his medical costs and has ignored requests for a copy of an incident report, his lawyer, Dean Vigliano said.

“It’s a shame when a dedicated hockey fan goes out for a night of enjoyment, and ends up spending a night in the hospital because of defective design and inadequate safety,” Vigliano said.

Silver, who hurt his neck, knee and hip in the incident, said he had seen others get struck by falling fans in the Brooklyn arena’s cheap seats but now that it’s happened to him, he’s done with the upper bowl at Barclays.

“I’ll never sit up there again. It’s just too dangerous,” he said. “It’s not a normal arena.”

Barclays Center complies with the city’s safety codes and “was built to the highest safety standards in the industry,” said the spokesman.