When I came back to normal, I felt my heart thumping wildly and there was a bitter taste in my mouth. It seemed as if a scorching blast of hot air had passed through my body. The feeling of exhaustion and weariness was more pronounced than it had been yesterday. I rested for some time to recover my strength and poise. It was still dark so I had no doubts that the experience was real and that the sun had nothing to do with the internal lustre that I saw. But, why did I feel uneasy and depressed? 

Instead of feeling exceedingly happy at my luck, why had despondency overtaken me? I felt as if I were in imminent danger of something beyond my understanding and power, something which I could neither grasp nor analyse. A heavy cloud of depression and gloom seemed to hang over me. I did not feel I was the same man I had been a few days before. A condition of horror, on account of the inexplicable change, began to settle on me, from which I could not make myself free by any effort of my will. Little did I realize that from that day onwards I was never to be my old normal self again. 

I had unwittingly and without preparation or adequate knowledge, roused to activity the most wonderful power in man. I had stepped unknowingly upon the key to the most guarded secret of the ancients, and thenceforth for a long time, I had to live suspended by a thread, swinging between life on the one hand and death on the other, between sanity and insanity, between lights and darkness, between heaven and earth. 

Source: Kundalini Path to Higher Consciousness by Gopi Krishna