I stay up so much because of work. How can find time to relax my body and mind?

Write down problems. Before you go to bed, write down your problems, how you hope to approach them tomorrow. Leave all of your issues on that piece of paper, knowing that you will address them at some other point, freeing yourself up now to go to sleep. Pick up a book, let your mind wander to a more comfortable place, and as you lie down reading, you will eventually drift off to sleep. Or have a timed musical piece.