I've seen an episode of the TV show "Alias" in which a character
mentions that she employs "autocircadian meditation," which she says
provides all the benefits of sleep without any unconsciousness, in a
fraction of the time. I'd like to get more information on how I can
get started learning about this practice, if it does in fact exist. If
it does not, I'd also like to know if there are any other valid sleep
alternatives I could consider.

Library of Congress results for autocircadian: 0
Useless links turned up by google: 6,980

If you want to reduce the amount of time you sleep consider a
polyphasic sleep schedule.  Information is readily available on
wikipedia.org:
http://en.wikipedia.org/wiki/Polyphasic_sleep

Results from other search engines provided no clues to autocircadian meditation.  

Multiple sites that returned an actual webpage made no reference to it
reducing the amount you need to sleep.  Typically those sites simply
add the key word searched to appear to meet your search needs:
http://www.beeswaxcandlessite.com/AUTOCIRCADIAN%20MEDITATION.shtml

Hope this helps a little bit.