I was going to mention ketamine. Famous for this type of effect. I don't want to belittle the meaningful experience, but the mind is a really powerful organ and it's a safer bet to treat these experiences as arising from mind rather than beyond it. Shrug.
>>it's a safer bet to treat these experiences as arising from mind rather than beyond it
Your brain has to be alive and exist normally for it to have these experiences. So its quite obvious, nothing is coming from outside of it.
I do feel like its some kind of brain rebooting itself or something like that.
Its sad babies can't tell us if they experience the same during childbirth, but I have a guess that they experience something similar as well.
Its just that the brain is starting up and checking if there is a OxDEADBEEF or a fresh boot. And giving you the primal, brain not initialising any other interface(like eyes, ears, limbs etc). You experience what life would be if only brain existed on its own without everything else apart from it.