For creepy chills, listen to the account of reporter Steve Volk's deeply unsettling recurring dream, which haunted him for 20 years before he conquered it through lucid dreaming. From a Radiolab episode.
Just pray you don't suffer from visions of the Old Hag (a common hallucination experienced during sleep paralysis, often experienced by narcoleptics and chillingly described by fictional narcolpetic Nicholas Benedict) should you choose to pursue lucid dreaming. Shudder.
"The Nightmare" by Peter Füssli, 1781
Happy Halloween (and sweet dreams)!