National Geographic : 2010 May
• Army sergeant from St. Louis. Her job is to train soldiers in hand-to-hand combat. Specializing in Brazilian jujitsu, Dinges says she is one of the few women in the Army certi ed at level 2 com- bat. Level 2 involves a lot of training with two attackers on one, she explains, with the hope of "you being the one guy getting out alive." Dinges may face an even harder ght in the years ahead. She belongs to a family carrying the gene for fatal familial insomnia. e main symptom of FFI, as the disease is o en called, is the inability to sleep. First the ability to nap disappears, then the ability to get a full night's sleep, until the patient cannot sleep at all. e syndrome usually strikes when the su erer is in his or her 50s, ordinarily lasts about a year, and, as the name indicates, always ends in death. Dinges has declined to be tested for the gene. "I was afraid that if I knew that this was something I had, I would not try as hard in life. I would allow myself to give up." FFI is an awful disease, made even worse by the fact that we know so little about how it works. A er years of study, researchers have gured out that in a patient with FFI, malformed proteins called prions attack the su erer's thalamus, a structure deep in the brain, and that a damaged thalamus interferes with sleep. But they don't know why this happens, or how to stop it, or ease its brutal symptoms. Before FFI was investigated, most researchers didn't even know the thalamus had anything to do with sleep. FFI is exceedingly rare, known in only 40 families worldwide. But in one respect, it's a lot like the less serious kinds of insomnia plaguing millions of people today: It's pretty much a mystery. ' we can't sleep, it's in part because we don't really know why we need to sleep in the rst place. We know we miss it if we don't have it. And we know that no matter how much we try to resist it, sleep conquers us in the end. We know that seven to nine hours a er giving in to sleep, most of us are ready to get up again, and 15 to 17 hours a er that we are tired once more. We have known for 50 years that we divide our slumber between periods of deep-wave sleep and what is called rapid eye movement (REM) sleep, when the brain is as active as when we're awake, but our voluntary muscles are paralyzed. We know that all mam- mals and birds sleep. A dolphin sleeps with half its brain awake so it can remain aware of its underwater environment. When mallard ducks sleep in a line, the two outermost birds are able to keep half of their brains alert and one eye open to guard against predators. Fish, reptiles, and insects all experience some kind of repose too. All this downtime comes at a price. An ani- mal must lie still for a great stretch of time, dur- ing which it is easy prey for predators. What can possibly be the payback for such risk? "If sleep CHERYL DINGES IS A 29-YEAR-OLD ByD.T.Max Photographs by Maggie Steber D. T. Max's book, e Family at Couldn't Sleep, explores the mystery of fatal familial insomnia. Maggie Steber photographed the story on memory in the November 2007 issue of Geographic.