Sri Aurobindo
Letters of Sri Aurobindo
Volume III - Part 4
The Power that is above your head has not only to be in connection with you, but to occupy the consciousness with its influence. The restlessness is due to a resistance of the lower consciousness which is not accustomed to the process by which this is done and probably feels uneasy – as you say you feel everything unsure. The body becoming unreal and all of one seeming to disappear are very usual results of the higher consciousness taking hold of the mind and they are very good signs – so too the sensation 
spreading from the head to the body is probably only the Power coming in. There should be no apprehension, for these things are quite normal in the transforming process. Probably the sense of unsureness is due to the part of the nature which founds itself on the body consciousness and feels nothing sure or solid except the body. In the new consciousness on the contrary what will be felt as sure and solid is the wide spiritual consciousness not limited by the body, in which the body is only a small circumstance hardly felt, an instrument only. The losing all consciousness must also be due to the consciousness going entirely inside as soon as the restlessness is forgotten or is no longer active.