Sri Aurobindo
Letters of Sri Aurobindo
02. The Triple Transformation: Psychic – Spiritual – Supramental
The force which you felt must evidently have been a rising of the Kundalini ascending to join the Force above and bring down the energy needed to ease the depression and then again rising to enforce the connection between the Above and the lower centres. The seeming expansion of the head is due to the joining of the mind with the consciousness of the Self or Divine above. That 
consciousness is wide and illimitable and, when one rises into it, the individual consciousness also breaks its limits and feels wide and illimitable. At such times one often feels as if there were no head and no body but all were a wide self and its consciousness, or else the head or the body is only a circumstance in that. The body or the physical mind is sometimes startled or alarmed at these experiences because they are abnormal to it; but there is no ground for alarm,– these are usual experiences in the yoga.