https://slatestarcodex.com/2019/10/21/the-pnse-paper/

Perhaps the most universal change in what PNSE participants reported related to their sense of self. They experienced a fundamental change from a highly individualized sense of self, which is common among the ‘normal’ population, to something else. How that ‘something else’ was reported often related to their religious or spiritual tradition(s), or lack thereof. For example, Buddhists often referred to a sense of spaciousness while Christians frequently spoke of experiencing a union with God, Jesus, or the Holy Spirit depending on their sect. However, each experienced a transformation into a sense of self that seemed ‘larger’ and less individuated than the one that was experienced previously. Often participants talked about feeling that they extended beyond their body, sometimes very far beyond it…

This change was dramatic and most participants noticed it immediately, even if initially they could not pinpoint exactly what had occurred. Sense of self changed immediately in approximately 70% of participants. In the other 30% it unfolded gradually, with the unfolding period reported as varying from a few days to four months.

Those who were not involved in a religious or spiritual tradition that contextualized the experience often felt that they might have acquired a mental disorder. This analysis was not based on emotional or mental distress. It was typically arrived at rationally because the way they were experiencing reality was suddenly remarkably different than they had previously, and as far as they could tell different from everyone they knew. Many of these participants sought professional mental health care, which no participant viewed as having been beneficial. Clinicians often told them their descriptions showed similarities to depersonalization and derealization, except for the positive nature of the experience.

There were nuances within how sense of self was experienced at different locations along the continuum. In the earliest locations, the sense of self felt expanded, and often seemed more connected to everything. In the farthest locations on the continuum, an even more pronounced change occurred in sense of self; a ll aspects of having an individualized sense of self had vanished for these participants. Prior to this location some aspects of an individualized sense of self remained, and participants could occasionally be drawn into them.

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Martin says that participants who moved from one level of his continuum to another (whether forward or back) would always say that the level they were currently at was the most fundamental and obviously real (even if they had said the opposite before). When he would tell participants about the experiences of other participants who were at different points of the continuum or just describing their experiences a slightly different way, both participants would confidently pronounce that the other wasn’t really enlightened.