All of which is to say, as far back as we can trace Western civilization, buried among the stories that bore schoolchildren to tears, we find tales of rebel upstarts willing to bet it all for an altered state of consciousness.
The Tunnel and Star There is an experience that practitioners of spinal breathing pranayama may encounter. It can happen just about anywhere along the way, or not at all until much later. It is not necessarily a measure of progress, but more of a confirmation. One of many that we can encounter as our practice advances.