I was meditating, and attempting to notice mental and physical sensations as they occurred. At some point, I tried instead to be conscious of nothing, rather than of these sensations, after which I experienced a sense akin to implosion -- a loss of contact with the world. This was accompanied by sustained strong muscle contractions in my head and body, which caused visual flares and rushing in the ears. I'm just curious as to .. what that was It seems a little like descriptions of the A&P, followed by Dissolution. I'd previously experienced sustained muscle contractions while meditating, but they were accompanied by feelings of rapture (which I think closely matches descriptions of the first jhana), whereas this experience was unpleasant and disorienting.