A number of religions, legends, and belief systems describe shadowy spiritual beings or supernatural entities such as shades of the underworld, and various shadowy creatures have long been a staple of folklore and ghost stories.

The Coast to Coast AM late night radio talk show helped popularize modern beliefs in shadow people.^[2] The first time the topic of shadow people was discussed at length on the show was April 12, 2001 when host Art Bell interviewed Native American elder Thunder Strikes, who is also known as Harley “SwiftDeer” Reagan. During the show, listeners were encouraged to submit drawings of shadow people that they had seen and a large number of these drawings were immediately shared publicly on the website.^[3] Later that year, on October 1, 2001, Heidi Hollis published her first book on the topic of shadow people. On April 7, 2002, Hollis discussed this book on the Coast to Coast AM show and was invited back as a regular guest, which helped to further define modern beliefs in shadow people.^{[citation needed]}Hollis described them as dark silhouettes with human shapes and profiles that flicker in and out of peripheral vision, and claimed that people had reported the figures attempting to “jump on their chest and choke them”.^[4] She believes they can be repelled by invoking “the name of Jesus”.^[5]

Although participants in online discussion forums devoted to paranormal and supernatural topics describe them as menacing, other believers and paranormal authors do not agree whether shadow people are either evil, helpful, or neutral, and some even speculate that shadow people may be the extra-dimensional inhabitants of another universe.^[2][6] Some paranormal investigators and authors such as Chad Stambaugh claim to have recorded images of shadow people on video.^[7]

Shadow people feature in two episodes of ITV paranormal documentary series Extreme Ghost Stories, where they are described as “black masses”.^[8]

Explanations

Several physiological and psychological conditions can account for reported experiences of shadow people. These include sleep paralysis,^[9] illusions,^[10] or hallucinations brought on by physiological or psychological circumstances, drug use or side effects of medication, and the interaction of external agents on the human body. Another reason that could be behind the illusion is sleep deprivation, which may lead to hallucinations.^[11]

In popular culture

• Shadow people, described as “Shadow Men”, feature prominently in the 2007 novel John Dies at the End. When they kill a person, that person is retroactively erased from existence, and history is rewritten as though they were never born.^[12]
• The 2013 movie Shadow People depicts a sleep study conducted during the 1970s in which patients report seeing shadowy intruders before dying in their sleep. The movie follows a radio host and CDC investigator who research the story, and the story is claimed to be “based on true events”.^[13]
• In the online game Deep Sleep and its sequels, shadow people have existed since the dawn of the human race and lurk in lucid dreams. Players who realize that they are asleep can be paralyzed and possessed, and the character’s dream self will turn into a shadow person.^[14]