The image of the sad clown, laughing on the outside while crying on the inside, has become so prevalent that it's practically become cliché. Yet, as is the case with many clichés, there's an underlying truth. In fact, the so-called "sad clown paradox" has actually been the focus of scientific study, exploring how the likes of beloved comedian Robin Williams , Spike Milligan of Britain's "The Goon Show," and "Friends" star Matthew Perry were plagued with crippling depression while bringing laughter to the world.

To a certain extent, the same can be said of Stephen Colbert. He came to prominence as a deadpan correspondent alongside host Jon Stewart on "The Daily Show," before spinning himself as a one-man parody of Fox News in Comedy Central hit "The Colbert Report," which launched in 200

See Full Page