A Dolbargy sleeping trance was a voluntarily induced deep coma that simulated 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. Quark witnessed the incident, though he did not recognize it for the trick that it was. (DS9: "The Nagus")

In the script, the sleeping trance was of Hupyrian origin. [1]