Possibly they mean more than one thing, but the primary concept that jumps to mind is known as the “dark night”. The aim of many meditation practices is to become aware of the contents of consciousness to the extent that those contents lose any emotional valence and become meaningless objects. In the long term this makes the meditator extremely equanimous and calm and detached, in a good way. In the medium term, before the changes have properly sunk in, it can result in a semi-detachment from reality where everything seems meaningless but in a very bad way.
I think I may have touched the edges of such phenomena. It is indeed unpleasant, and probably contributed to my cutting down my meditation by a lot.
Possibly they mean more than one thing, but the primary concept that jumps to mind is known as the “dark night”. The aim of many meditation practices is to become aware of the contents of consciousness to the extent that those contents lose any emotional valence and become meaningless objects. In the long term this makes the meditator extremely equanimous and calm and detached, in a good way. In the medium term, before the changes have properly sunk in, it can result in a semi-detachment from reality where everything seems meaningless but in a very bad way.
I think I may have touched the edges of such phenomena. It is indeed unpleasant, and probably contributed to my cutting down my meditation by a lot.