Why Does the Manas, Which Continually Scrutinizes and Deliberates, Still Need Sleep?

Sleep is for restoring the energy of the physical body and eliminating its fatigue, so that the six consciousnesses can operate normally, better, and more effectively. The manas regards the physical body as its own possession, regards the six consciousnesses as its own possessions, and regards the five aggregates and eighteen realms all as its own possessions; moreover, it relies on the eighth consciousness to know the condition of the physical body in every instant. The activity of the six consciousnesses consumes energy. In order to reduce this consumption, the manas decides not to let the six consciousnesses continue their activity, and actively shuts off the six consciousnesses' discernment of the six sense objects, no longer wishing to know the six sense objects, relying only on the manas's own knowing. In this way, energy continuously accumulates, and once vitality has recovered to a certain degree, the manas will decide to wake up, make contact with sense objects, and continue the activity of the five aggregates.

If the physical body becomes fatigued, sleep is needed to restore energy, and the manas will decide to sleep, no longer letting the six consciousnesses be active. The manas itself wishes to shut off the six sense objects and not cognize them; thus the five sense consciousnesses and the mind consciousness gradually cease. Therefore it is not that the manas needs sleep, but that the physical body needs rest, to replenish energy and restore vitality. This is precisely the result of the manas's continual scrutiny and deliberation. However, sleep does not affect the manas's continual scrutiny and deliberation; the manas can continue deliberating during sleep, and can even manifest dream states, deliberating within them.