Do we only use 10% of our brain? - Conscious and subconscious (Sleep paralysis & Lucid Dreaming)

Do we only use 10% of our brain ? This myth establishes that most of the human brain is unused, suggesting that we only use a small portion of it and because of this some kind of secret power can be unleashed, turning us into superheroes able to use telekinesis, telepathy and so on. One possible origin is the reserve energy theories by Harvard psychologists William James and Boris Sidis in the 1890s who tested the theory in the accelerated raising of child prodigy William Sidis.