Dolbargy sleeping trance was a voluntarily induced deep coma that simulates death.

Zek, the Ferengi Grand Nagus, used the technique to fake his own death in 2369 when he wanted to test the readiness of his son, Krax, to serve as Nagus. Zek's servant, Maihar'du, had taught him the technique. (DS9: "The Nagus")