The term 'It's in Your Head' can be broken down into three crossword solutions: EYE (3 letters), IDEA (4 letters), and GRAYMATTER (10 letters). The first solution, EYE, is a reference to the physical organ that is used for vision. The second solution, IDEA, is a concept or thought that is formed in the mind. The third solution, GRAYMATTER, is a scientific term for the brain and its associated neural pathways. Together, these three solutions suggest that the phrase 'It's in Your Head' is referring to the IDEA that thoughts and ideas originate from within the mind.