designation: 1986 JK) is a highly eccentric, sub-kilometer-sized carbonaceous asteroid that is thought to be an extinct comet.
The asteroid was discovered by American astronomer couple Carolyn and Eugene Shoemaker at the Palomar Observatory in California on 5 May 1986.
Hypnos may be the nucleus of an extinct comet that is covered by a crust several centimeters thick that prevents any remaining volatiles from outgassing.
[7] According to the NEOSurvey carried out by NASA's Spitzer Space Telescope, Hypnos measures 520 meters in diameter and its surface has an albedo of 0.22 based on an absolute magnitude of 18.65,[4] while infrared radiometry gave a radar albedo of no more than 0.067 and a diameter of at least 740 meters.
The official naming citation was published by the Minor Planet Center on 6 January 2003 (M.P.C.