Possible Duplicate:
How did the letter Z become to be associated with sleeping/snoring?
In old cartoons and even now in other such media, often the letters 'zzz' are used to indicate that a person is sleeping. What is the origin of this? It seems that the sound that someone makes when they are snoring isn't zzz at all, but rather, as a friend put it, a series of rolling rrrrrs.
