The “Nightmare King” isn’t just a seasonal name thrown on Burger King’s latest burger.

The quarter-pound beef burger topped with chicken, cheese, bacon, onions, and mayo, on a green sesame seed bun, is “clinically proven to induce nightmares,” according to the burger chain.

A new ad shows participants hooked up to sleep monitoring machines after eating the burger. Per USA Today, the incidence of nightmares increased 3.5 times over the normal rate, apparently due to various proteins. “I remember hearing voices and people walking around talking,” one participant says, per People.

The burger will be available for $6.39 from Oct. 22 through Nov. 1. (Burger King previously tried a black bun.)

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