DELIRIUM

Delirium is a state of mental disorder characterised by disorientation of reality, changes in perception of the world around us, as well as impaired thinking and consciousness. 

At the time of delirium, a person may experience a wide range of visual, auditory, tactile, and kinesthetic sensations that may be incorrect and distorted
The reality of delirium for the person in this state is distorted and altered. One may experience hallucinations, illusions, and panic ideations that do not correspond to actual reality. For surrounding observers, the reality of the delirium may be unclear, as the person's behaviour and statements may be unpredictable and incomprehensible.

It is not clear to the end who the main character in the film is, or what is even happening. Where is reality and does it exist at all?