Are you desperate to find a solution to a problem? Have you looked everywhere for a solution? Maybe you are a programmer and you have tried to find the error everywhere in the code, but you are unable to find it? Or are you creating an Excel sheet, but you cannot make the graph look the way you want it to look?
Are you writing a thesis, but you don't know how to progress? You need to look where everyone else has looked, but at the same time be able to see what no one else sees. That is important, but sometimes you need to follow the advice of Einstein and just go to bed.
"To achieve the impossible, one must think the absurd; to look where everyone else has looked, but to see what no one else has seen. And sometimes, to get ahead, one must simply get some sleep." - Albert Einstein
Sometimes you are able to see things from a different perspective and in a different way after you have slept. Sleep can perform miracles when it comes to problem-solving and creativity.