... there are reports from China in the "old days" (and even now) of monks [especially during Sesshin] meditating with just about 3 hours of sleep (or pulling an "all nighter" or two or more). In Dogen's day (sometimes still now), they used a special wooden support called a "Zenpan" to hold the chin up (true), and were actually just sleeping in the Lotus Posture (I have done that too, although it is discouraged these days most times).
"Zenpan" description here:
http://books.google.com/books?id=smNM4E ... en&f=false
Here is one:
I have posted this from time to time on Zazen and sleep (and becoming sleepy during Zazen) ...
Originally Posted by Jundo