In the early morning, when I was dozing off, I suddenly felt a sensation of something expanding, like water flowing through a hose, in the area around my coccyx. This sensation 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 in the back of my chest and stopped there.

The speed was not very fast, like water flowing through a channel, but even so, it probably took about 5 or 10 minutes for it to reach my chest. I was dozing off, so the time is not precise, but 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). The Chitra nadi, in particular, is said to be strongly connected to the Brahma Granti located in the Muladhara chakra.

When people talk about Kundalini, they often use the analogy of "flame," and it's often associated with a hot and strong energy. In my case, that kind of hot and burning energy has become quite normal, or rather, it was a past experience. This time, it was just a slight difference, as if a thin line was added to it.

Therefore, because of this, it's difficult to determine what this experience was.

One hypothesis is that the Brahma Granti is starting to dissolve, and a thin but quite certain energy has begun to flow through the central Chitra nadi (Brahma nadi) within Sushumna.

Sushumna is relatively on the outer side, and I think that when energy begins to flow through Sushumna, heat is generated, and even that can significantly activate one's life. That's what they say about Kundalini energy, 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 like it was flowing through a very fine and central part of my spine. If that's the case, it might be the Chitra nadi rather than Sushumna.

Or, it might be the Vajra Nadi located outside the Chitrak Nadi. However, based on the diagrams, the Vajra Nadi and Sushumna seem to represent largely the same thing, so I'm inclined to think it's the Chitrak Nadi. What do you think?

Sushumna (outer) → Vajra Nadi (middle) → Chitrak Nadi (center)

I will continue to observe this further.

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