Like the off-balance characters in Hitchcock's "Vertigo" (remember that spinning spiral graphic?), people who get hit with benign positional vertigo can't be sure of what's up - or what's down. And for the more than 160,000 North Americans diagnosed every year, that makes it hard to drive (you never know when an attack might hit) or feel comfortable with physical activity (just tilting your head can trigger an episode).

Turns out, there's a lot going on inside the inner ear we're unaware of, until something goes wrong. In the canal-like vestibular system, tiny particles float on even tinier hairs. The motion of the particles against the hairs triggers electrical messages to the brain that let you know where up and down are. They're sort of gravity meters. But if those particles end up in an adjacent area called the cupula, the world starts spinning. Nausea and anxiety follow. Although attacks may last only 30 seconds to 2 minutes, they're discombobulating.

Treatment has depended on something called the Epley Maneuver, which is a series of motions (usually requiring two people) that are designed to get the ear's fluid and particles back in the right position. When such position-adjustments don't work, surgery is an option. But an afflicted researcher at the University of Denver's School of Medicine devised a simpler Half Somersault motion done on your own. It's effective and prevents recurring attacks better than the Epley.