We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember saying
something like:

While In the room affected by the most recent event he
muttered that someone had told him that the ceiling might have
asbestos in it but to me this sounds very unlikely . It's just the
original L+P ceiling as far as I could tell from what I saw when
looking up at the hole.

Is it really likely that asbestos was used in a ceiling ?

Nup. Highly unlikely - I know those old Glasgow ceilings from having
some fall on me as a kid and I can tell you there's all sorts of ****e
in the void, but asbestos is highly unlikely.
Did you notice if the ceiling void was filled with a clinkery material
for soundproofing?