Kundalini
And in the category of sounding like I might be insane:
I've experienced this and I've done a little poking around. This is my OPINION and I'm not citing anything.
1. The chakras all correspond to hormone producing organs.
2. I believe Kundalini is most likely a cascade of hormones from the hormone producing organs.
3. There are TWO kinds of Kundalini. One starts at the top of the head and flows down and feels vaguely like warm water in a waterfall only not. The other starts in the loins and flows up and feels more like a dry heat or a fire inside.
4. In my experience, it CAN be a thing that happens in sexual situations OR it can happen independently for physical health reasons.
I am including it here because it may be pertinent for people pursuing HRT.