And while the cause of most of these sleep remnants is fairly obvious, the reason behind those sometimes-sticky, sometimes-crusty gobs of crud that can dot the lashes or cling to the corners of the eye is less clear.
Santa's Little Helper's initial appearance on The Simpsons was in the first episode of the series, Simpsons Roasting on an Open Fire, which aired on Dec. 17, 1989. Since then, he has become a recurring character.
The episode has all the trappings of a heartfelt goodbye to one of television's best programs. Creator Matt Groening makes a cameo. We learn what happens in the future to the Simpsons family. And the Christmas setting makes for a nice bookend to the show's pilot, Simpsons Roasting on an Open Fire..