My father, who was a schizophrenic and a Theosophist, sometimes talked about the Kundalini fire: he said that he felt that it sometimes began to rise up along his spine, and when it reached his temples, he became psychotic.
Funny enough, though I have always been more schizoid than bipolar, I have had one hypomaniac episode in my life. I used to say that it was hypomaniac, but when I recently described the onset of that hypomania to one friend who had worked as a nurse in a mental hospital, he said that it resembled a full mania rather than hypomania.
It was almost midnight 47 years ago, I was very, very bored, I did not know if I should go to bed or try to write something. I remember having looked at the clock, and it was almost midnight. Then -- something sudden electrified me, five minutes passed, and when I looked at the clock again, it was 4 am. Four hours had passed without me noticing it! Every place was full of half-smoked cigarettes, I had drank liters of coffee, every place was full of papers with scribbling. This was the beginning of it: soon it became a little milder, but for a couple of months I slept only every second night and was extremely talkative and felt that life was a great gift.
But what is interesting is that earlier that evening I had felt very, very restless and anxious with no obvious reason. I found 80 mg of Librium (benzodiazepine) somewhere, swallowed it and then lied on our kitchen floor in the savasana position trying to relax, and slowly the anxiety passed. This was about four hours before the mania began. And I remember clearly that during that anxiety I thought of the fire of Kundalini that my father had described; I also felt that something was rising up from the lower part of my spine, and that something made me extremely nervous.
So? I'm an atheist, I cannot believe in life after death, I don't know if I believe in any Kundalini, but it is possible the old yogis knew something about such phenomena, whatever they are. My father used to say that if you are not mature enough, such a fire just makes you crazy.
Note that I lost all interest in yoga when I stopped believing in reincarnation -- and this was more than 50 years ago. One of my nieces practices yoga and says that if you stand on your head and meditate, you cannot get covid, and I just think she is a crackpot.
But sometimes I just wonder: what if some phenomena like Kundalini really exist? (I don't even know what it exactly is.)
This mania happened 47 years ago, as I said.