MLB

YANKEES HELP CAMP BRIGHTEN SPIRITS OF LIGHT-SENSITIVE KIDS

IT IS a little after 11 p.m. Friday night, which means Katie Mahar, 15, could go outside and play if she so desired. It is some 19 hours after Yankee Stadium was magically transformed into her field of dreams, when the New York Yankees shined the brightest rays of hope possible into the hearts of mostly young children who are forced to live in darkness.

Caren Mahar has five children. Katie is the one afflicted with Xeroderma Pigmentosum (XP), a rare, insidious genetic disorder that causes the body to be unable to repair cells damaged by ultraviolet light. She and her husband, Dan, 14 years ago co-founded Camp Sundown, a year-round night camp for sun-sensitive children and their families, in Craryville, N.Y.

“Last night,” Katie said over the telephone, “was amazing.”

Clowns, magicians and Yankees, all at the beck and call of Katie, her brothers Danny (22), Brendan (19) and Patrick (6), 24 frolickers in all, 11 with XP, ranging in age from 9 to 32, and 13 siblings. She watched her first baseball game from a party suite before all heaven was about to break loose.

“Nobody goes on the Stadium field except the players and maintenance,” Caren told the group. “They didn’t know about what was going to happen down there.”

This is how MLB.com described the scene: “With upbeat pop music filling the air, the scoreboard was transformed into the world’s biggest video-game screen as campers took turns playing ‘MLB ’09 The Show’ from the visitors’ dugout. An inflatable bounce tent popped up in left-center field, and hot dogs were being cooked on the warning track by the visitors’ bullpen.

“Magicians wandered the outfield showing off card tricks, and several of the pitchers tossed Wiffle balls to the campers, truly giving them the opportunity to hit off a Yankee. Alfredo Aceves even provided some of the entertainment, strumming an acoustic guitar in center field and singing from the John Mayer catalog.”

All that, and frisbees in the air too.

“Everyone had a blast,” Katie said. “I won the trivia game! I got it right on the first shot!” What did she win? “I won a $25 Modell’s gift card,” she said.

What did Katie think of the Stadium?

“I think it was huge!” she said.

Yankees director of media relations Jason Zillo, whose HOPE (Help Others Persevere and Excel) Week home run made him the Babe Ruth of community outreach, introduced Caren on the field to Jorge Posada, whose 9-year-old son Jorge IV has endured numerous surgeries for his craniosynostosis, a condition that causes malformation of the skull.

“So tell me about your son,” Caren said, and Posada did. And then brought his good cheer and compassion over to Katie, who was diagnosed with XP in 1996.

“We talked about camp and we talked about the Yankees . . . Posada is a very, very outgoing person,” Katie said. “He was all smiles around everyone.”

Katie also got to meet Yankees reliever David Robertson. The carnival ended at around 4 a.m. and the Camp Sundown guests boarded the bus to beat sunrise back to their home-away-from-home.

“It was bubbly for a little while,” Caren said, “then everyone was pooped out. They just blew themselves out!”

Camp Sundown returned home with a $10,000 check from the Yankees. Caren searched for the right word to sum up what the experience meant for her.

“Awe is the only word I can think of,” she said. Asked what she would say about the Yankees, Caren said: “They’re the best! They’re the only baseball team going.”

steve.serby@nypost.com