During yongmaeng chôngjin, the monks in meditation hall do not sleep for seven
straight days, breaking from their practice only for meals. They even skip the
dinner ritual in the main Buddha hall so as to devote themselves completely to their
meditation. In this intensive period, the monks face one another in two separate
rows down the middle of the meditation hall, rather than facing away as they
usually do. ... Otherwise the meditation sessions take place pretty much as
always, with fifty-minute sitting periods followed by ten minutes of walking. ...
Other than its obvious interminableness, the major difference between
yongmaeng chôngjin and regular meditation periods is that the large warning stick
(changgun chukpi) is in use constantly throughout each sitting period....
If the drowsy monk does not react to the guard's presence, the guard taps
him on the shoulder with the stick and gives him one round of blows.
As grueling as yongmaeng chôngjin might seem to the uninitiated, its purpose is
not to torture the monks. Rather it provides an incredibly intense, but still carefully
controlled, environment in which to meditate. The hope is that several days of
sleeplessness will apply enough pressure on the meditators that they will be able to
have a genuine breakthrough into their meditation topics, or hwadu ("critical
phrase" [of a Koan, such as "MU"]). Just before yongmaeng chôngjin begins, the Son master tries to impress
upon the meditators that the only way they will be able to survive the week is to
remain concentrated at all times on their hwadu and to arouse the sensation of
doubt. From my own experience, the sheer enormity of the task of remaining
awake for seven straight days was enough to frighten me into focussing on the
hwadu, as if I were clinging to it for dear life. The instant the mind wavers, you are
bludgeoned by bone-numbing fatigue, so the only hope you have of getting through
the week is to maintain your concentration.
http://www.persee.fr/doc/asie_0766-1...3_num_7_1_1069