Somniloquy

Somniloquy (som-NIL-uh-kwee) noun

The act or habit of talking while asleep.

[From Latin somnus (sleep) + loqui (to speak).]

Today's word in Visual Thesaurus: http://visualthesaurus.com/?w1=somniloquy

"Somniloquy can occur in all stages of sleep (both dream and nondream
sleep), though individuals awakened while talking in their sleep will
often recall dreaming. Sleep talking usually does not result in
significant problems for individuals; however, it may be embarrassing
if noted by family or friends."
Sleep Talking Usually Not Serious; The Cincinnati Post; May 4, 2004.

Source: A.W.A.D.