Whenever you sleep your consciousness is transported to simulated reality designed by your power to provide various methods to experiment and train your power to its fullest extent in a safe environment. Powers with limited resources do not consume them in this world. There is no sapient life in this world, just soulless Automata for you to practice on. This world and your body in it is entirely mental/simulated only useful to build skill and muscle memory. Time spent in Super Dream counts as proper sleep for the purposes of body maintenance. It is not just powers this helps train if you for example wish to develop your skills as a mechanic it will provide opportunities for you to develop the skill as long as you put the work in, do this enough times for multiple different disciplines and people might think you have a tinker power or multiple thinker powers even if this is your only power.