All that free time over the holidays had us watching TV in a whole new way. ‘Twas the season of the cable-TV marathon, a hypnotic marketing tool that gets us disturbingly amped. And we’re not the only ones: More and more networks are running marathons (and not the 26.2-mile kind) to promote their series or just fill out a sleepy Sunday afternoon. Bravo, for instance, airs blocks of current-season reruns to stoke audiences for new episodes of its reality franchises (Top Chef, The Real Housewives of Orange County), a technique it came upon three years ago to lure new viewers to the fledgling first season of Project Runway. SOAPnet, on the other hand, regurgitates daytime shows in five-episode blocks on weekends. ”Your life gets in the way of your TV viewing,” says Brian Frons, the Disney-ABC president of daytime who oversees SOAPnet. ”Marathons are a great chance to catch up.” SOAPnet also cleans up with the occasional nighttime-drama marathon — the New Year’s Day One Tree Hill run mesmerized more than 1.1 million viewers. What the heck is wrong with us that we can’t look away from, say, 16 consecutive episodes of recycled Top Models, or — heaven forbid — One Tree Hill? Is it nostalgia? Laziness? A Pavlovian response? ”When you sit down to a marathon you never think you’re going to watch a show for six hours,” says Sarah Tomassi Lindman, The N’s general manager. ”It’s like eating a bunch of M&M’s instead of a whole candy bar.” And with upcoming marathons that include The N’s Saved by the Bell (Jan. 14) and ABC Family’s cheer-tastic Bring-It-On-A-Thon (Jan. 18 — 20), we’re planning for some serious sugar shock.