The disjointed, illogical, and often, fantastical nature of dream sequences lend themselves nicely to a visually stimulating and satisfying cinematic experience.
Daniel Manus, an L.A.-based script consultant wrote on the role of dreams in enhancing your screenwriting experience. Dreams are a succession of images, thoughts, sounds, or emotions which pass through the mind during sleep – when one’s mind is not consciously in control of said things.
As they pass through our subconscious and conscious minds, dreams affect us at a visceral level and generate a powerful emotional response which resonates with both characters and audiences alike. Although influenced by the reality of our daily lives, they are not an account of it.
Dreams can be a powerful character development tool as they have the power to explore one’s secret desires, scars, fears and bring to light a character’s subconscious motivations, conflicts and values, while still leaving things up to interpretation by audiences. Dream sequences provide a temporary reprieve from the main plot, allowing audiences’ imaginations the opportunity to wander and process theme.
Dreams are used in film a great deal because they can employ different visual or auditory elements that can give your script a specific and distinct style, texture, tone and help give subtext and dimension to a character.
Daydreams can reflect the truth more accurately because you are awake, however more often than not daydreams take a fantastical approach to reality or illuminate some sort of fantasy more than an accurate real-life occurrence.