Sleep could be the cornerstone of consciousness research, particularly by following in the wake left by Giorgio Vallortigara on corollary discharge and delving into the allostatic phase of sleep (altered state of consciousness different from wakefulness, in which, for example, hallucinations are present).

Hypnagogia is the transition between wakefulness and sleep. During this state, it's common to experience visual, audio, or other types of hallucinations. It's also common to experience muscle jerks and sleep paralysis.

The hypnagogic state: A brief update - PMC.

What is a corollary discharge in psychology?

A neuronal signal that encodes a copy of an intended motor command, which is sent to a structure in the brain (a brain comparator) that can compare the intended movement with the sensory feedback (reafference) that results from the actual movement. From: corollary discharge - APA Dictionary of Psychology

The efference copy signal as a key mechanism for consciousness

With the words of Carmelo Bene, stepping outside the discussion and using some abstraction: