Can self-investigation boost the mind or kuṇḍalinī or cause sleeplessness and other health issues?

A friend wrote to me saying ‘I keep on practicing Self-Enquiry and I feel that the practice of Self-Enquiry affects the kundalini in my body and for some reason boosts my mind’, and he went on to describe other problems that he felt were caused by his practice, particularly sleeplessness and other health issues. This article is adapted from the replies I wrote to him.

Learning how to be self-attentive

A friend sent me a series of three emails, in the first of which he wrote:

With regards to Self-investigation, I have a few questions:

1. Am I investigating the ego/individual self, with the aim of finding the falsity of it?
2. Or am I investigating the true Self, with the aim of uncovering my true nature?
3. What is the best approach to achieve the goal?

Could what exists ever not exist?

A friend wrote to me:

I recently watched your YouTube video discussing the above verse [the first maṅgalam verse of Uḷḷadu Nāṟpadu] as I was having some troubles understanding it. I have a few questions that have not been cleared yet. It is about the first sentence of that verse: