Master Dogen wrote this about his teacher, Master Nyojo’s, attitude toward sleep …

When staying at Tendo Monastery in China, while the old master Nyojo was abbot there, we sat zazen until about eleven o’clock at night and got up at about half-past two to sit zazen. The abbot sat with the assembly in the sodo, never taking even one night off.

While sitting, many monks fell asleep. The abbot walked around hitting them with his fist or his slipper, scolding them and encouraging them to wake up. If they continued to sleep, he went to the shodo1, rang the bell, and called his attendants to light the candles. On the spur of the moment he would say such things as; “What is the use of sleeping? Why do you gather in a sodo? Why did you become a monk and enter this monastery? … It is utterly foolish to pass the time you are alive meaninglessly sleeping or lying down while you fail to practice the buddha dharma. …