The Seventeen Gallery on the Kingsland Road in London has recently presented an exhibition (hurry, last day tomorrow) of the many recordings of Dion Mcgregor's sleep; the most well known voluable and coherant sleep-talker in history.
http://en.wikipedia.org/wiki/Dion_McGregor
Mcgregor is often accused of being a hoax, because his ramblings in his sleep have an eleoquence and coherance that has never been come across before, he was able to describe, or rather speak aloud, his incredibly vivid dreams as it happened. Soon the friends he stayed with realised this phenominom occured several nights of the week, and his Somiloquys would often last the whole night- so they started recording them when they occured. 100s of recordings were made, some pressed onto LP and commercially available (!!) and the Seventeen Gallery's basement presents some of these as they were recorded, and edits some to extract certain narratives. It is very peturbing to hear these recordings, particularly as they are presented in a pitch-black basement, but some of the dreams and his voices are so utterly absurd you may find it funnier than is intended.
Dion Mcgregor's sleep recordings were very numerous, and will be available on the internet, somewhere...