Meditative Concentration Can Reduce the Consumption of the Four Great Energies

When there is meditative concentration (samādhi), one needs less sleep, and the body does not require too much sleep. This is because meditative concentration itself can reduce the activity of the six consciousnesses, thereby lessening the consumption of the four great elements' nourishment. Meditative concentration can also reduce the manas's grasping and engagement, decrease the activity of the physical body, and lessen its pulling upon and control of the entire nervous system. The brain's nervous system, the five internal organs and six viscera, and the whole body can then move and consume the four great elements less, so the body does not become fatigued, and the manas does not need to decide on sleep.

The deeper the meditative concentration, the less sleep is needed—to the point where one can completely stop sleeping. This is because at that time the manas is very tranquil, no longer wishing to engage in any activity, and thus no longer excessively mobilizing the brain's nervous system; there is very little activity of the body faculty and of the conscious mind. The more concentrated the manas, the less it grasps and engages, the less it regulates and controls, the less it consumes of the four great elements, and the less it needs sleep and food.

Some people, in their daily work, do a great deal of work yet have very few mental thoughts; their consumption is low, so they do not need to eat so much food, do not need so much sleep, and still remain full of energy. This shows that what consumes the energy of the four great elements the most is the mental activity of the manas, while the six consciousnesses themselves do not consume very much. Therefore, even though the workload of the six consciousnesses is not reduced in the slightest, when the manas's mental thoughts decrease, the amount of activity decreases, and the work no longer feels tiring.

From this we can see that the manas can grasp and understand the condition of the physical body anytime and anywhere, and can regulate, control, and direct it anytime and anywhere. He discerns with great agility and subtlety, not coarsely at all. The mind consciousness does not even know the various conditions of the body, and still needs the manas to hint and alert it.