The Gray Team with Maj. Jennifer Bell (center), who ran a concussion clinic, seen in the Helmand province of Afghanistan in 2010: Col. Michael Jaffee (from left) , Capt. James Hancock, Col. Geoffrey Ling, Lt. Col. Shean Phelps and Col. Robert Saum. Courtesy of Christian Macedonia hide caption

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Courtesy of Christian Macedonia

How A Team Of Elite Doctors Changed The Military's Stance On Brain Trauma

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Katherine Du/NPR

Kit Parker's Story Part I

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Most people who say they've had a concussion say they sought out medical care at the time. Science Photo Libra/Getty Images hide caption

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Science Photo Libra/Getty Images

Poll: Nearly 1 In 4 Americans Reports Having Had A Concussion

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Months after a concussion or other traumatic brain injury, you may sleep more hours, but the sleep isn't restorative, a study suggests. iStockphoto hide caption

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iStockphoto

A Concussion Can Lead To Sleep Problems That Last For Years

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Before Monday, no NFL official had publicly acknowledged a link between football and chronic traumatic encephalopathy. Here, members of the Denver Broncos are seen after one of their teammates suffered a concussion during a game in late 2014. Doug Pensinger/Getty Images hide caption

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Doug Pensinger/Getty Images

In A First, NFL Executive Admits Football Is Linked To Brain Damage

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John Castello decided to stop playing football when he learned about the risks of brain injury. Dave Marmarelli/DGM Photography hide caption

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Dave Marmarelli/DGM Photography

The Impact Of 'Concussion': High School Football Player Changes Course

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Garrison Pennington (right, No. 42) tackles a player during Albany High School's 2014-2015 season — the last he would play. Courtesy of Ned Purdom hide caption

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Courtesy of Ned Purdom

Quitting The Gridiron When Football Runs Through The Family

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NFL Confidential HarperCollins hide caption

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HarperCollins

'NFL Confidential': Anonymous Player On Why He Loathes The League

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The Alto Yellowjackets take the field on Nov. 13, a month after Matthews died. Lauren Silverman/NPR hide caption

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Lauren Silverman/NPR

Deaths Persist In Youth And Student Football Despite Safety Efforts

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Germany's Alexandra Popp and the U.S.'s Morgan Brian collide during a World Cup semifinal in June. Both were injured, but continued to play. Brad Smith//ISI/Corbis hide caption

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Brad Smith//ISI/Corbis
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Concussions Can Be More Likely In Practices Than In Games

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High school athlete Graham Hill, number 50, suffered a concussion in 2013 while playing football at Trinity Christian Academy in Addison, Texas. Courtesy of Jeffrey McWhorter hide caption

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Courtesy of Jeffrey McWhorter

High Schools Seek A Safer Path Back From Concussion

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Making and taking a hit chest to chest, instead of skull to skull, is easier to remember if you're not wearing a helmet, say University of New Hampshire Wildcat football players. Jack Rodolico/New Hampshire Public Radio hide caption

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Jack Rodolico/New Hampshire Public Radio

Football Players Drill Without Helmets To Curb Concussions

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Go Big Green! Dartmouth is testing the VGo robot to help diagnose concussions when neurologists aren't at the game. Mark Washburn/Courtesy of Dartmouth-Hitchcock hide caption

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Mark Washburn/Courtesy of Dartmouth-Hitchcock

Walt Whitman High School's Caroline Schweitzer runs through a host of Severna Park High School defenders during a semifinal game in Maryland's Class 4A/3A lacrosse tournament in May. Toni L. Sandys/The Washington Post/Getty Images hide caption

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Toni L. Sandys/The Washington Post/Getty Images

Junior Seau sustained many concussions during his career and was suffering from a degenerative brain disease when he killed himself in May 2012. Otto Greule Jr./Getty Images hide caption

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Otto Greule Jr./Getty Images

Researchers have only recently been able to use brain scans to detect Alzheimer's risk factors in living people. iStockphoto hide caption

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