America has recently become quite fascinated with zombies, with the walking dead becoming a staple of movies, TV shows and other forms of pop culture. However, what most do not know is that there are actually some people who sincerely believe that they are the walking dead, according to The New York Hyde Patch.

The belief that one is already dead is called Cotard's syndrome, named after the French neurologist who first diagnosed the mental delusion after working with a female patient who was firm in her belief that she was already dead.

Author Esmé Weijun Wang was among the people who experienced the syndrome firsthand. In November 2013, Wang came to the conclusion that she had been dead for a month. Her belief was bolstered by a fainting incident on a flight home from London to San Francisco. According to Wang, she believed that she actually died during that flight, reports The Washington Post.

"I was convinced that I had died on that flight, and I was in the afterlife and hadn't realized it until that moment. That was the beginning of when I was convinced that I was dead. But I wasn't upset about it, because I thought that I could do things in my life over and do them better," she said.

Though she was interacting with her husband and their dog, Daphne, Wang believed that they were dead as well, and that they were sharing an afterlife together.

Dr. Michael Birnbaum, director of North Shore-LIJ Health System's Early Treatment Program, said that people suffering from the delusion are at risk, mainly due to their belief that their physical life has already ended.

"Any delusion can be incredibly dangerous depending on how it impacts your life," Birnbaum said. "Someone who believes they're already dead may not take the necessary steps in their daily life - to shower, get out of bed, go to work, go to school or have healthy relationships and friendships. None of those things matter if you're already dead."

Though Wang was able to conquer her delusions, she said that she still feels fatigue, weakness, insomnia, as well as joint pains. For her, however, these inconveniences are nothing compared to the despair that she felt when she saw herself as a rotting corpse.

For more health news, click here.