Mors–Somnus was discovered on 14 October 2007, by American astronomers Scott Sheppard and Chad Trujillo with the Subaru Telescope at Mauna Kea Observatories in Hawaii, United States.

[3] The object is a wide optically resolved binary with the following orbital parameters: The components have almost equal size.

[3] The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.1 and calculates a diameter of 175.20 kilometers based on an absolute magnitude of 6.9.

[3] The minor planet was named after the mythological twin Roman gods of death (Mors) and sleep (Somnus).

[2] The approved naming citation was published by the Minor Planet Center on 2 June 2015 (M.P.C.