By Stephanie Stahl

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PHILADELPHIA (CBS) – New findings on children and concussions show they experience symptoms longer than adults and too much rest may not be the best remedy. Fifteen-year-old Grace Kamvakis has a mean spike but volleyball has not always been her game.

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Grace grew up playing soccer. Three years ago, she was hit in the head with a soccer ball two different times.

Her concussion symptoms lasted six months.

“Headaches, obviously,” said Kamvakis. “Sensitivity to light. Sensitivity to noise, dizziness. I couldn’t use computers or anything.”

“She had a headache for a long time,” said Grace’s mother, Heidi Kamvakis.

Now research in the Journal of American Osteopathic Association says children under age 13 experience concussion symptoms much longer than older teens and adults.

“Up to four weeks and longer, than adults – adults, more like two weeks,” said Dr. Hallie Zwibel, Director of NYIT Center for Sports Medicine.

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And, experts now say total rest after suffering a concussion is no longer recommended as long as symptoms don’t return or get worse.

“We found that more than 48 hours of strict rest has actually negative consequences. So getting children, adolescents, adults back in their activities – school, work is actually producing better outcomes,” said Dr. Zwibel.

Researchers stress athletes should not compete if they are experiencing symptoms and for lingering problems, vision and balance rehab can help.

That’s what got Grace back on her feet.

“Obviously I wanted to be on the field but it’s better to just sit out and get better,” said Kamvakis.

She still worries about suffering another concussion but says being able to use her hands playing volleyball makes her feel a bit safer.

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The study also finds children with ADHD, depression or anxiety may have concussion symptoms that last even longer.

Stephanie Stahl