Whether this can be called meditation or not is a matter of opinion... However, as part of the meditation process, I forcefully push and expand the skull in the forward and outward directions.

When I say it like this, it may sound metaphorical, but in reality, although it is happening little by little, it is actually occurring rather than being a metaphor.

When focusing consciousness through the Kechari Mudra and aiming to relax a specific point, areas that were previously stiff will expand with the influence of its vibrations.

I will repeat that many, many times.

Sometimes, there is a sharp, piercing sensation or slight grinding pain at the border between muscles and bones. However, this is temporary, and the pain subsides as it spreads and resolves. I understand that this is a transient state during skull expansion.

When it expands, energy (prana in yoga) flows more easily through that area and becomes activated.

According to traditional stories, the spread of this type of skull can sometimes occur in a relatively short period, perhaps around one month. However, in my case, it seems to have been ongoing for several years, which may be because the original bone is too hard and takes time to expand.

Recently, I have become quite accustomed to it, and since I know that this will eventually end someday, I think "well, there's nothing I can do about it," so I am continuing with a long-term approach.