Burger King is getting ready for Halloween by making a burger bun with a difference.

The "Nightmare King" will have a ghoulish green bun and is filled with grilled beef, crispy chicken, bacon, American cheese and mayonnaise.

And Burger King is actually claiming that the Halloween sandwich will induce nightmares, having tested it with 100 people over ten nights. The study revealed a 3.5 time increase in nightmares.

It's the combination of protein and cheese that leads to vivid dreams, according to Dr Jose Gabriel Medina, a somnologist and the study's lead doctor, according to an online release Wednesday. People's Rapid Eye Movement (REM) cycles were interrupted, a time when most people dream.