There are two explanations, but I cannot figure out an experiment to distinguish them.
1) the brain continues to process during the period where brain activity is deemed 'low', and such there's ongoing consciousness (in the form of hallucinations). This is akin to what we assume happens in the dreaming state.
2) the brain rapidly hallucinates a memory as it's "coming to". In other words, it was off but then forms connection as it's waking up that are interpreted as memory. This is akin to the Deja Vu phenomenon, where we experience real-time stimuli as (partially) the replay of a memory.
1) the brain continues to process during the period where brain activity is deemed 'low', and such there's ongoing consciousness (in the form of hallucinations). This is akin to what we assume happens in the dreaming state.
2) the brain rapidly hallucinates a memory as it's "coming to". In other words, it was off but then forms connection as it's waking up that are interpreted as memory. This is akin to the Deja Vu phenomenon, where we experience real-time stimuli as (partially) the replay of a memory.