A Kryptonian trance is a trance used by Kryptonians to put oneself into a deep comatose-like state, making them appear dead. While under this trance, a Kryptonian can survive the effects of Kryptonite for a much longer time, but only Kryptonian science is able to revive them. On two occasions, due to exposure to Green K, Superman placed himself in a Kryptonian trance, and everyone believed he was dead. Once in 1985, and then again a few years later in 1988. On both occasions it was advanced equipment from the Fortress of Solitude that revived him.