The phrase "racks brains" refers to the act of using one's mind extensively to come up with a solution, idea or plan. However, sometimes we need to take a break from "racking" our brains and instead, relax and take time off. A few antonyms for "racks brains" include leisurely activities such as taking a walk in nature, reading a book, watching a movie or simply engaging in a hobby. Another antonym might be to collaborate with others and seek help in finding solutions rather than trying to do everything on one's own. Remember, taking a break can help refresh our minds and lead to new insights and ideas in the future.