Where's the data on how little sleep I can get away with?

I don't know if it's a fact that software developers as a group operate sleep deprived for long periods of time before catching up, but anecdotally I know it to be true. It's certainly something I struggle with on a daily basis.

Yesterday when I saw this NY Times article titled "How little sleep can you get away with?" I thought it was great, made me think I maybe should change my ways:
http://www.nytimes.com/2011/04/17/magazine/mag-17Sleep-t.html

I re-read it this morning because I wanted to know where the sleep deprivation to productivity inflection point was. How long can I go with sleep deprivation before the increased amount of awake but impaired time becomes counter productive? Frustratingly it's not in the article. This is the kind of bad reporting I can't stand anymore. I don't want paragraphs of "story", I want a short description and then tables of data. This is the kind of thing Mythbusters would easily and clearly have nailed in a simple table.

How much sleep to get is particularly tough because with kids, wake up time is totally out of your hands. I wrote SleepMute for Mac (available on the Mac App Store) mostly to guarantee uninterrupted sleep from my always on Mac's sound alerts when I do hit the sack.
http://www.tangerineelement.com/main/sleepmute.html

Ironic I developed the app to help with uninterrupted sleep using a lot of sleep deprivation.