The Pratyutpanna Samādhi Sūtra is one of the early Mahayana sutra, in which stated the contemplation method of all present Buddhas in ten directions. By practicing according to such contemplation method, one can attain “Pratyutpanna Samādhi” and see the Buddhas appear in his Samādhi. During Later Han Dynasty, Lokakṣema (147-246) brought this sutra to China, and translated it in to Chinese in year 179 A.D. In his Chinese translation of Pratyutpanna Samādhi Sūtra, there are quite several of places, Chinese terminology terms “eliminate sleep” (除睡眠, 除睡臥,棄於睡眠, 不得臥出) appear. The Chinese practitioners commonly comprehend such terms as “do not sleep”, even in the “middle night” (2-6am). Consequently, a method which emphasizes on “do not sleep” within 90 days developed in China, and has been widespread until nowadays. However, is it possible without sleeping for 90 days? Although my intuition suggests that it is impossible, there was not a few number of practitioners have put it into practice in the past. Anyway, I found that Harrison (1998) in some places of his English translation of Pratyutpanna Samādhi Sūtra, has translated “除睡眠” etc. as “eliminating sleepiness”. At the same time, I found that “除睡眠” (do not sleep) in Pratyutpanna Samādhi Sūtra are translated as “除睡蓋”（eliminate torpor） in the parallel sutra called Bhadrapāla Sutra (《賢護分》). They suggest that “除睡眠” can represent two meanings, which is “not to sleep” and “eliminate torpor”. Between these two, which is the most proper and fit better to the whole context of Pratyutpanna Samādhi Sūtra? This is the main problem statement of this paper, and I have made a deep study towards this topic by following four steps. First of all, I have clarify the whole framework of practice contained in Pratyutpanna Samādhi Sūtra, and determined the position of “eliminate sleep” (除睡眠) in the whole framework. The result suggests that the practice of “eliminate sleep” (除睡眠) is not the main factor that let a practitioner to attain Pratyutpanna Samādhi, the main factors are: empowerment of the Buddha, the force of Samādhi, and the force of one’s virtues collected in the past. If anyone wish to improve the force of Samādhi, he should practice regarding following steps: “ preserve the śilā → stay in a lonely place → recollect the Buddha → single mindedly recollect the Buddha → see the Buddha(s) → practice the insight of śūnyatā.” Secondly, a comparative study of Chinese, Tibetan and English versions of Pratyutpanna Samādhi Sūtra has been made, and the result suggests that “除睡眠”should take the meaning as “eliminate torpor” rather than “do not sleep”. Thirdly, since there is a common viewpoint stated that Pratyutpanna Samādhi Sūtra is based on tradition of dhūtaguṇa, a deep study has been made regarding this tradition, and it shows that the practitioners of dhūtaguṇa do actually sleep during middle-night, but they sleep in sitting posture, since they are not allowed to lie
