These days, even a tap on the head can cause high school senior Niki Popyer to lose consciousness. Headaches are her constant companion, she's not allowed to drive, and she can't concentrate on her school work.

Her predicament can be traced to a series of concussions she has suffered since she was in seventh grade - the first seven from playing basketball and five more that have been caused by incidents as innocuous as bumping her head on a car door.

The plight of Popyer and other young athletes whose lives have been altered by this often misdiagnosed and misunderstood injury is the target of a House bill that seeks to fund education, diagnosis and treatment efforts.

"No doctor told me to stop playing - they'd say, 'Sit for one or two days and you'll be fine,'" Popyer said at a hearing Wednesday hosted by the bill's sponsor, Rep. William Pascrell Jr., D-N.J., and Rep. Frank Pallone Jr., D-N.J., the chairman of the House Energy and Commerce Subcommittee on Health.

Afterward, she said that she has to avoid any situation with potential for a collision. "I can't ride the train because they're afraid I might bump into somebody."

A concussion is a jostling of the brain that can be caused by a direct blow or even a sudden stop. It doesn't necessarily cause unconsciousness, but symptoms can include headaches, nausea, dizziness, sensitivity to light and noise and trouble concentrating.

If sustained repeatedly over time, even so-called mild concussions can have a cumulative effect and lead to long-term brain damage, Dr. Vic Kapil of the Centers for Disease Control and Prevention's National Center for Injury Control and Prevention, said during the hearing.

Awareness of the potential damage from concussions apparently is on the uptick. A study on organized youth sports published in Pediatrics magazine this month found that emergency room visits for concussions for 8- to 13-year-olds doubled from 1997 to 2007. For 14- to 18-year-olds, they tripled. Still, experts believe far more concussions are never reported.

"I played all the sports growing up, and in my neighborhood if you came out of the game, you were a sissy," Pascrell said. "That was stupid."

Some of the heightened attention can be attributed to research into brain damage suffered by retired NFL players who had suffered multiple concussions.

Former NFL player Roman Oben, an offensive lineman who played from 1996 to 2007 for San Diego, Tampa Bay, Cleveland and the New York Giants, referred Wednesday to former New York Jets wide receiver Wayne Chrebet, whose career was cut short in 2005 after a series of concussions.

"There are two or three guys like that on every team," Oben told the congressmen. "You go out and play with pain because there are two or three guys waiting to take your place. I've seen guys not remember their cell phone numbers, not remember their home address."

Pascrell's bill, the Concussion Treatment and Care Tools Act, or ConTACT, seeks to establish guidelines for prevention, identification and management of concussions, including standards for when student-athletes can return to play after suffering a concussion. It also would offer grants to schools to conduct computerized neuropsychological testing both pre- and post-injury for comparison.

"Young people are resilient and don't want to get sidelined by bumps and bruises, but head injuries shouldn't be ignored," Pallone said. "We must aim to provide our school administrators, coaches and athletic directors with the right information and tools needed to protect athletes from the dangers of repeated head injuries and developing long-lasting cognitive issues."