Over the weekend, 352 people paid good money for the absurd privilege of running nine loops — in a row — around Central Park. (That’s one five-mile loop plus eight four-mile ones, adding up to 60 kilometers, or 37.2 miles.) The race began at 8 a.m., and the last runner didn’t cross the finish line until 5:30 p.m. To recap: That is nine-and-a-half hours — your entire work day — spent running.
Run 30, 50, or — good lord — 100 miles in a row, and some weird things will start to happen to your brain and body, as the Washington Post reported last week; among the weirdness, according to the Post, are hallucinations. “When you run around the clock, extreme fatigue and strange shadows in the wee hours can sometimes play havoc with your mind,” writes Bonnie Berkowitz. “A nap usually fixes the problem.”
And that’s it. That’s all they gave us on the mind games an ultramarathon can play on runners. To find out more, Science of Us contacted Martin Hoffman, a professor of physical medicine and rehabilitation at UC Davis who has studied ultramarathoners; he’s also an ultrarunner himself. In his early days as an ultramarathoner, Hoffman said he would sometimes imagine that he saw some huge, terrifying animal creeping along the path — although, he says, this is not the best example, because so many of these races take place in areas where bears or mountain lions probably are creeping along the path.
In some cases, Hoffman explained, these tricks of vision may be caused by actual eye problems. “We know of this phenomenon that we refer to as ‘ultraeye syndrome’ — which is probably the development of corneal edema, which can impair vision,” Hoffman said. This means that the cornea — the outer surface of the eye — has swollen to the point where it obstructs vision. It’s not yet clear why this happens to ultrarunners, but “it can get so bad that people can’t continue,” he explained. “Basically, all they can see is some light and maybe some shadows, that sort of thing.”
True hallucinations, on the other hand — in other words, becoming convinced you’re seeing something that isn’t really there — can be caused by fatigue or sleep deprivation; this can happen to anyone, and so it’s not all that surprising that this should occasionally happen to people who run for dozens of miles at a time, sometimes through the night. It’s never happened to Hoffman himself, but he has heard some weird stories. “I’ve heard people say bizarre things, like they’re seeing a military ship cruise by,” he said.
No one has published any peer-reviewed research on hallucinations among ultrarunners, but as part of his thesis at the University of Texas at El Paso, Andrew Mojica surveyed the runners of the 2003 Badwater Ultramarathon, the infamous 135-mile course that begins in the depths of California’s Death Valley and ends at the trailhead to Mount Whitney, at an elevation of more than 8,000 feet. Thirty percent of those runners said they’d hallucinated at some point during the race.
One woman — known only as Participant D — experienced some truly frightening visions. “Her visual hallucinations consisted of terrifying images of rotting corpses watching her every move, and following her during the race.” Mojica wrote. “She also saw giant beetles and ‘mutant mice monsters’ crawling on the road. She heard noises from behind her, but didn’t want to check their source. She also described a tactile hallucination of something pushing or grabbing her.”
Just, you know, in case you needed an additional reason to not run 100 miles at at time.