Have you heard the one about the groomsman who locked his knees during the wedding ceremony and passed out cold? Or the guy who gets weak at the knees every time he enters a hospital? Maybe you’re one of those queasy types who can’t see blood without seeing stars.
But have you heard about roller coasters?
“All I know is I couldn’t see what was going on, and I shook my head vigorously to try to keep myself from passing out,” wrote blogger and roller coaster enthusiast Karol Gajda about his experience on a ride at Six Flags Over Texas.
“Sometime during the vertical loop after the first drop, I experienced a momentary grayout in which I saw spots,” reported a commenter on the online forum Theme Park Review about his trip to Kings Dominion in Doswell, Virginia.
While there’s no way to know exactly how often such experiences occur on roller coasters, blacking out or “graying out” during rides is medically understandable, experts say.
“At the bottom, you get squished by all of this G-force and, as my [neurologist] friend put it, there’s a very small range between the thrill and the kill,” says Orly Avitzur, a neurologist in Tarrytown, New York, who serves on the American Academy of Neurology’s board of directors. “The blood that should be in the brain pools at the feet very quickly, and your brain isn’t getting [enough] blood or oxygen,” which can cause a momentary loss of vision or consciousness. Some riders, too, may experience “redouts,” or the sensation of seeing red caused by blood rushing to the head rather than away from it.
Is that cause for concern? U.S. News talked with Avitzur and her colleague Neil Busis, a clinical professor of neurology at the University of Pittsburgh, to find out what thrill seekers should know during this season of screams.
Know the Risks
Roller coasters, needless to say, have their ups and downs. In the best case, riders experience the thrill of a lifetime; in the worst case, they die. (Fortunately for the adrenaline junkies among us, death by roller coaster is rare.) Nevertheless, there’s a host of possible reactions in between that receive less attention, such as blackouts, strokes and whiplash effects, Avitzur says.
“One of the scariest things that can happen — and there have been medical reports about this — is that the arteries in the neck can dissect,” she adds. That means an artery wall’s inner layer begins to tear, which can lead to stroke. “There aren’t that many case reports of these,” Avitzur says. “But there are enough to make you pause and think about that risk factor.”
Other roller coaster-related cases reported in medical journals include barotrauma, or a pressure trauma often in the ear, and pulmonary hemorrhage, or bleeding into the lung. Passing out, too, may cause seizures or even permanent brain damage, though Busis is unaware of any instances of that happening on a roller coaster. “More likely, it’s just a transient thing,” he says. “It’s just a couple of seconds and you come to and you’re fine.”
[Read: 10 Ways to Lower Your Risk of Stroke.]
Know Your Risks
In her practice, Avitzur sees lots of patients with herniated discs and other spine and neck conditions. It’s those people who most frequently return to her with problems post-roller coaster. “If you have a herniated disc, that’s already precarious,” she says. “Too often you’re at risk of making it worse, much the same way a car accident would make it worse — that whiplash effect.”
Other people who may want to think twice before strapping in to a wild ride are pregnant women, those with heart problems, people on blood thinners or who have low blood pressure and people with anemia. The lower your blood count, the harder it is for the blood to reach your brain when put to the test.
And if you’re someone who’s prone to graying out or even fainting in everyday circumstances — say, when you stand up too quickly? You’re a good candidate for a roller coaster blackout, Busis says. “We see a lot of people who pass out in medicine,” he says. “And I think the risk factors for passing out are going to be the same, just magnified with roller coasters.”
[Read: So You’re Getting a Pacemaker.]
Take Pre (and Post) Cautions
In one case study reported in the journal Laryngoscope, a young man riding a roller coaster turned to his girlfriend just as the ride began to accelerate. He wound up at the doctor’s office with pain and a sense of “fullness” in his right ear. Although the rider was back to normal in a few days, the story prompted the researchers to recommend amusement parks instruct riders to face forward throughout the ride.
Experts also recommend staying hydrated before and during your amusement park visit, since dehydration alone may be enough to make you lightheaded. It’s also important to see a doctor as soon as possible after a roller-coaster ride if you notice any changes in pain or functioning since some conditions, like arterial dissections, can become more severe over time. And remember, just because your friends are lining up for the wildest new ride, you can always sit one out.
[Read: Why Some of Us Are Thrill-Seekers .]
“People always just have to assess risks and benefits, and [consider] individual human physiology,” Busis says. “One ride doesn’t necessarily fit all.”
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10 Questions Doctors Wish Their Patients Would Ask
Roller Coaster Blackouts: Safe or Scary? originally appeared on usnews.com
Correction 10/09/14: A previous version of this story mistakenly interchanged low blood pressure and low blood count.
