• by Wayne Friedman , June 18, 2009

Just 2 weeks old, "The Tonight Show with Conan O'Brien" has become a much younger viewer program than its predecessor. With O'Brien helming NBC's big late-night enterprise, the show has lopped 10 years off its median age -- now at 45.7, down from Jay Leno's 55.7.

CBS' "Late Show with David Letterman" remains in the older territory; its viewers had a median age of 56.7.

Much of this change is due to O'Brien's stronger appeal in the 18-34 demographic, which is 177% higher than CBS' "Late Show with David Letterman," where it has 1.040 million viewers to Letterman's 376,000. In particular, males represent a big chunk of this 18-34 group, giving O'Brien 545,000 to Letterman's 158,000.

Late-night programming is crucial for TV advertisers in targeting younger viewers, according to TV analysts.

Letterman has gotten closer in total overall viewers, but they seem to be an older demo, perhaps abandoned by Leno. For the week of June 8-12, the second week on the air, O'Brien beat Letterman by just 100,000 viewers -- 3.8 million to 3.7 million.

Leno had been averaging a much higher total viewer number recently -- 5 million viewers, which is more than 1.2 million over O'Brien's current average. Some of this is due to lower overall viewing levels in the summer.

Even among the broader demographics of younger viewers 18-49, O'Brien maintains a healthy advantage in his second week -- a 1.5 rating/6 share, which amounts to 2.013 million viewers. This compares to the 0.9/3, or 1.126 million from "Late Show."

NBC also dominates with its other late-night effort: "Late Night with Jimmy Fallon" earned 1.14 million 18-49 viewers in comparison to CBS' "Late Late Show with Craig Ferguson," which saw some 665,000 in the most recent week.