In the deep sleep state we lay down our ego [ahankara],our thoughts and our desires. If we could only do all this while we are conscious, we would realise the Self. The best form of dhyana or meditation is when it continues not merely in waking but extends to the dream and deep sleep states. The meditation must be so intense as not even to give room for the consciousness of the idea “I am meditating.” As waking and dreaming are fully occupied by the dhyana of such a person deep sleep may be considered to be part of the dhyana.
