Why does Theo think he is dreaming?

Theo thinks he is dreaming because he experiences a series of surreal and disorienting events that challenge his perception of reality. The bizarre occurrences around him, coupled with a sense of detachment from his surroundings, lead him to question whether what he is experiencing is actually happening or merely a figment of his imagination. This confusion creates a feeling of unreality, prompting him to believe he is trapped in a dream.