Why is the letter Z associated with sleep?

<i>"you know what they call sleeping in the UK? Catching some zeds."</i><p>We do? Literally never heard that, not a single time.<p>As to the fact that it comes from snoring... am I the only one who thought it was obvious as soon as I read the title?

Here's a more pertinent question:<p><i>Why is this on the front page?</i>