October means Halloween is coming—you know, the very witching hour of night when churchyards yawn and graves give up their dead and so on. But if you're still picking out your costume—and you're looking for something a little scarier than Sexy Donald Trump—you might need a refresher course, because it's surprising how much we don't know about some of our most iconic monsters. Luckily, Jeopardy! monster Ken Jennings has unchained his debunking abilities and is ready with the spooky scoop.

The Debunker: Was Sunlight Fatal for Bram Stoker's Dracula?

If there's one thing that vampires take seriously, it's their sleep schedule. If they're not back in their casket full of Transylvanian soil by daybreak, they know they'll soon be hissing and sizzling like a strip of bacon. Sunlight is fatal to Dracula, everyone knows that. The photophobia of vampires a powerful trope in our culture, affecting everything from the cinematography of our horror movies to the complexions of our Goth kids at the mall.

But if you actually go back and read Bram Stoker's Dracula, the 1897 novel that gave birth to the modern vampire myth, you're in for a surprise. Jonathan Harker, visiting Dracula in his castle, does write in his journal on June 25, "I have not yet seen the Count in the daylight. Can it be that he sleeps when others wake, that he may be awake whilst they sleep?" But Harker is mistaken: back on May 8, Dracula popped in to his chamber to wish him good morning while he was shaving. Not very vampire-like behavior.

Could Harker have been up shaving before dawn? Apparently not, because when the book's action shifts to Yorkshire and then London, Dracula continues to be the king of daytime (sorry, Regis), making no less than six more appearances in broad daylight. "It was possible, if not likely," says the vampire hunter Van Helsing, "that the Count might appear in Piccadilly during the day." Possible if not likely? The death-by-sunlight notion would not appear for 25 more years, in the iconic silent film Nosferatu that would first adapt Stoker's novel. The literary Dracula evidently prefers the night, but is not above a nice afternoon stroll if he needs to stretch his legs or return some videos or something. Does the London sunlight make him look all sparkly, like a Twilight vampire? Stoker, sadly, leaves us in the dark.

Quick Quiz: Dracula's homeland of Transylvania is today a region of what country?

Ken Jennings is the author of six books, most recently his Junior Genius Guides, Because I Said So!, and Maphead. He's also the proud owner of an underwhelming Bag o' Crap. Follow him at ken-jennings.com or on Twitter as @KenJennings.