Can a burger give you nightmares? That’s what the Burger King brand set out to prove with an unusual research study on its latest Halloween burger, the Nightmare King. The sandwich features ¼ lb of beef (pre-cooked weight), a white meat crispy chicken fillet, melted American cheese, thick cut bacon, mayonnaise, and onions—all assembled on a glazed green sesame seed bun.

In partnership with the Paramount Trials, Florida Sleep & Neuro Diagnostic Services Inc, and Goldforest Inc, the Burger King brand conducted a scientific study over 10 nights with 100 participants who ate the Nightmare King before they went to bed. By tracking various signals from the sleeping subjects including their heart rate, brain activity and breath, a group of doctors and scientists conjectured about whether the individuals had vivid dreams.

“Someone… transformed into the figure of a snake,” reported one of the study’s subjects when asked about her dream. Another recalled “aliens attacking” the boat he was on.

“According to previous studies, 4% of the population experiences nightmares in any given night,” says Jose Gabriel Medina, MD, sleep specialist and the study’s lead doctor, in a release. “But, after eating the Nightmare King, the data obtained from the study indicated that the incidence of nightmares increased by 3.5 times.”

Medina adds that the combination of proteins and cheese in the Nightmare King led to “an interruption of the subjects’ REM (rapid eye movement) cycles, during which we experience the majority of our dreams.”

The Nightmare King will be available in participating Burger King restaurants for a limited time beginning October 22 at a recommended price of $6.39.