In the early morning, when I was dozing off, I suddenly felt a sensation, though I'm not sure what it was, in the area around my coccyx, as if water was flowing through a hose. This sensation then traveled up my spine and gradually reached my chest. It was a very thin, but very solid line.

There wasn't any immediate change or anything like that, but eventually it reached the area along my spine behind my chest and stopped there.

The speed was not very fast, like water flowing through a channel, but even so, it probably took 5 or 10 minutes for it to reach my chest, although I was dozing off, so the time is not precise. It didn't seem to take that long.

In yoga, the spine is said to be the main route (nadi) for energy, called Sushumna. The word "Sushumna" is often used, but in reality, there are several lines within it, and "Sushumna" is just a representative term.

Within Sushumna, there are Vajra nadi and Chitra nadi (Brahma nadi), and Chitra nadi is said to be strongly connected to the Brahma Granti located in the Muladhara chakra.

When people talk about Kundalini, it's often described as a "flame," giving the image of a hot and strong energy. In my case, that kind of hot and burning energy state was quite common in the past, but this time, it was just a slight difference, as if a thin line was added to it.

Therefore, it's difficult to determine what this was, simply because it happened.

One hypothesis is that the Brahma Granti is starting to dissolve, and a thin but quite certain energy has flowed into the central Chitra nadi (Brahma nadi).

Sushumna is relatively on the outside, and I think that when energy starts to flow through Sushumna, heat is generated, and even that can significantly activate one's life. Kundalini energy is supposed to be something like that, but I think it's a relatively physical energy.

On the other hand, this time, I felt a line-like energy, a very thin but solid line, like a fishing line, that felt thin but strong and unbreakable, passing through the very central part of my spine. If that's the case, it might be Chitra nadi rather than Sushumna.

It might also be Vajra nadi, which is outside Chitra nadi, but based on the diagrams, Vajra nadi and Sushumna seem to mean almost the same thing, so I think it's more likely to be Chitra nadi.

Sushumna (outer) → Vajra nadi (middle) → Chitra nadi (center)

I will continue to observe this area further.

(The diagram is from MEDITATION and Mantras (by Swami Vishunu-Devananda), P91.)