Oneiro is a term in psychoanalysis that refers to the mental images that arise in a person during sleep. They are often a reflection of his internal conflicts, fears or desires. Oneiros represent elements of dreams and occur at the subconscious level. This is one of the types of autonomous activity of the individual. Oneiros are divided into two categories: 1. Simple - these are single oneiros that occur at the peak of sleep; 2. Complex - this is oneiro with fantastic images, rich in allegories.