The young flyer in seat 24B had her earbuds in and her pink sweatshirt hood up, eating her in-flight lunch of pasta, when the large middle-aged man sleeping next to her appeared to lurch awake.

“At first, he grabbed my shoulder,” the 21-year-old woman told a federal jury in Brooklyn in January. Then, “he went around, and he grabbed my right breast.”

The groping lasted 30 seconds before fellow passengers could pull them apart.

The woman’s attacker, Chris Karadimas, 57, of Brooklyn was brought up on serious federal sex-abuse charges. But he presented a bizarre defense, one that is being used increasingly often — and with considerable success — these days.

Sleep apnea made me do it.

“I know it sounds like an outrageous story, but when you hear all the testimony, you realize, yeah, that’s what happened,’’ Karadimas’s lawyer, Matt Galluzzo, told The Post.

Karadimas was eventually acquitted.

“Only in America,’’ one online commentator wrote.

Latin for “not breathing,” apnea has been around as a diagnosed sleeping disorder since the late ‘70s.

About 12 million Americans, half of them undiagnosed, are estimated to be affected by the condition — a relaxing of the throat muscles that results in the repeated blocking of breathing during sleep, causing extreme and often sudden exhaustion later.

But only recently has the condition become the excuse du jour in criminal and civil cases.

And so far, it’s working.

In the case of the airplane groping, Galluzzo was able to convince the jury that his client suffered from apnea and was so fast asleep on the trip that he mistook the woman’s breasts for the multiple pillows he usually uses to prop himself up in his bed back home. The jury apparently didn’t care that Karadimas also had stayed up all night and downed Scotch and Tylenol PM before the flight.

In another, more devastating, case, a Washington state man successfully used the sleep-apnea defense after he fell asleep behind the wheel and his car jumped a curb, plowing into a crowd of high-school kids and killing two teenage boys, just one week before summer vacation.

Defense experts testified that William Klein’s apnea had been interrupting his sleep some 30 times an hour each night, making him not criminally responsible for his sudden doze-turned-deadly.

In May, a jury agreed.

The sleep-apnea defense also cleared two engineers of criminal charges in a pair of New York City-area fatal train crashes: the 2013 Metro-North derailment in The Bronx that killed four riders and last year’s NJ Transit crash that killed a 34-year-old mom as she stood waiting on a platform at the Hoboken terminal.

So far, there are no criminal charges pending against the engineer in a third crash in January, when an LIRR train smashed into Atlantic Terminal in Brooklyn, injuring more than 100 people.

But sources told The Post that federal investigators are probing whether that engineer also may have suffered from sleep apnea.

Dozens of civil lawsuits are pending in all three crash cases. If any go to trial, the juries will likely be asked to again decide if sleep apnea is a valid defense.

“Isn’t it outrageous? ‘Excuse me, I’m not responsible because I fell asleep,’” seethed lawyer Howard Hershenhorn, who represents victim families in both the 2013 derailment and September’s crash at Hoboken Terminal.

“Why didn’t any of these very sleepy engineers just stop the train, or ask the conductor to take over?’’ Hershenhorn said.

“They didn’t have narcolepsy; they didn’t have a seizure. They fell asleep.”

Some sleep disorders have been used successfully as a defense for decades.

The first one to win a murder case was in Boston — in 1846.

Married father of two Albert Tirrell amazingly convinced a jury that he had been sleepwalking the whole time when he slit his prostitute lover’s throat — nearly decapitating her — and then set the brothel on fire.

But the first actual sleep apnea-murder defense, raised in 1994, did not work so well.

Michael Ricksgers, a 37-year-old welder from Pennsylvania, was convicted of murder after unsuccessfully claiming that his apnea-triggered exhaustion had him in such a deep sleep, he mistook his wife for an intruder — or maybe a deer — and shot her dead.

Only very recently has sleep apnea become the go-to diagnosis in defending against cases of fatal car and train crashes, experts said.

“I would think in cases of drowsy driving and vehicular homicide, certainly if I was on the defense side, I would evaluate the driver,” said Dr. Mark Pressman, one of the country’s foremost forensic sleep experts.

Pressman, who’s based in Ardmore, Pa., has consulted for both the defense and prosecution over the past 18 years, handling about eight to 10 cases a year where sleep disorders are raised as a defense.

But it took until last year for him to testify in his first sleep-apnea case — defending Klein, the driver in Washington.

Pressman helped convince the jury that the 35-year-old dad, whose 3-year-old son was sleeping in a back seat as he drove, had such severe apnea, he literally was fell asleep at the wheel without warning.

People such as Klein become so used to being grossly sleep-deprived over the course of months, even years, that they don’t realize anything is wrong with them, according to Pressman and other experts.

Apnea sufferers will claim to doctors that they feel alert, but their performance will be poor when tested. And when told to fall asleep, they’ll do so, however fitfully, in a minute or 2 flat, as opposed to the 15-to-20 minutes it takes for a healthy person.

“They’ve lost their frame of reference for what’s normal,” Pressman said. “This is what is normal for them.”

Pressman believes that Klein fell asleep at the wheel for only 5 seconds, just enough time for his car to jump the curb and kill Shane Ormiston, 18, and Gabriel Anderson, 15.

While prosecutors argued that Klein had disregarded the safety of others by knowingly driving while exhausted, Pressman told jurors Klein fell asleep without any warning whatsoever.

Still, while Pressman helped win the case for the defendant, he acknowledges he is concerned about one thing.

“[Apnea] may also unfortunately become a common excuse for people who don’t have a defense,” he said.

The lawyer for the engineer in the September NJ Transit crash says to bet on it.

Jack Arseneault, who is repping engineer Thomas Gallagher, said his client’s sleep apnea was so severe that he nodded off without warning — and yet a company physical two months before the crash revealed no problems.

The more the public becomes aware of the issue, the more defendants will turn to it as a defense, Arseneault told The Post.

The National Transportation Safety Board only first documented sleep apnea as the cause of an accident in 2000, when a Baltimore Light Rail train ran into the end-of-track bumping post at the Baltimore-Washington International Airport, causing nearly two dozen injuries, NTSB records show.

It took parent company MTA until 2015, two years after the derailment, to begin screening Metro-North engineers and conductors for sleep apnea.

And only after January’s LIRR crash did the MTA announce it will expand sleep apnea screening for all engineers and conductors on LIRR trains. Its subway and bus operators will also be tested.

But plenty of victims’ lawyers are gearing up to put the sleep-apnea defense to the test.

“There’s still negligence on the part of the engineer,” insisted lawyer Scott Rynecki, who said he has been retained by 10 victims in the January LIRR crash.

“There comes a point where you have to become aware of the symptoms, at least a few seconds before you fall asleep,” and ask for help or stop the train, he said.

“It’s not like on Abbott and Costello, when the hypnotist says, ‘You are getting sleepy,’ and you fall asleep.”

Robert Vilensky, the lawyer for LIRR crash victim Wanda Rich, who is suffered nerve damage and fractured ribs, is suing the MTA and engineer Michael Bakalo, 50, of Melville, LI, for a total of $15 million.

“It just seems to be a very convenient defense,’’ he said of the engineer’s alleged sleep apnea. “I’m not buying it.’’

But even the lawyer for Samuel Rivera — a former Metro-North mechanic who is the most seriously injured in the 2013 train derailment in The Bronx — said he believes that sleep apnea is a real concern.

He said that while his client “is going to be a parapalegic until the day he dies, and he has a 3-year-old kid,’’ he isn’t suing — or even blaming — engineer William Rockefeller.

Federal investigators have confirmed that Rockefeller fell asleep at the switch of a Hudson Line train due to undiagnosed sleep apnea, and “my gut feeling is apnea itself is legitimate,” Cannata explained.

Instead, Cannata puts the full blame for the accident on the railroad.

“The real tragedy, quite frankly, is that the danger of sleep apnea for train operators has been known for a long time — decades,” Cannata said.

The MTA has said through a spokeswoman that it does not comment on pending litigation.