• Forbes, Monday, June 15, 2009 9:30 AM

Contrary to popular belief, the average viewer of the late night talk shows of Jon Stewart and Stephen Colbert is more likely to be a hard-working Dad than a party-loving college student.

In May, the median age of "The Daily Show" viewers crept up five years to 41.4, and the median age of "The Colbert Report" viewers was up five years to 38.3, per Nielsen. The number of people between 18 and 34 (the most coveted demo for ads) fell 14% to 15% for both shows.

Ad rates aren't expected to decline because of viewers any time soon, but it's the kind of change that advertisers will keep an eye on. "When you start to see the age creep up on a show like that, you wonder whether the show is sustainable," says Laura Caraccioli-Davis, head of entertainment at Starcom. "It's systematic of the fact that at Comedy Central, they need to continue developing shows for younger viewers." To offer some perspective, the median age for "The Late Show with David Letterman" is 54, and Jay Leno's show attracted a median age of 55.

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