釋禪波羅蜜次第法門 2.116

2.116

Second, regulating sleep: sleep is a dharma that obscures through the delusion of ignorance, and although one must not indulge it, if one does not sleep at all, the mind and spirit become flighty and unsettled; if one sleeps excessively, not only does it waste the cultivation of the noble Dharma, but it also squanders one's efforts in vain, causing the mind to become dark and dim, and wholesome roots to sink away. One should be awakened to impermanence and tame sleep, so that the path of the spirit is pure and bright, and the mindful mind is clear and lucid; only then can one settle the mind in the noble realm, and samādhi will manifest before one. Thus the sūtra says: “During the early night and the later night, do not neglect [practice]; do not, on account of sleep, let an entire life pass in vain with nothing attained. Reflect on the fire of impermanence burning all worlds; quickly seek to deliver yourself, and do not sleep.”