SUBCONSCIOUS HOMICIDE.
[...]It is a well known fact that homicide may be committed in the somnambulistic and epileptic state while the normal consciousness of the individual has been wholly or partially suspended. Such acts are invariably attended by amnesia; they are usually motiveless, and nearly always so extremely impulsive as to suggest a reflex origin. The attendant circumstances and the person’s subsequent conduct are usually satisfactory evidence that the ordinary consciousness of the individual was obscured if not entirely obliterated.
Source: Charles P. Bancroft, "Subconscious Homicide and Suicide; Their Physiological Psychology," American Journal of Insanity 55 (October 31, 1898): 264