A pen is an instrument used to do work. When you dream of a pen, you are obsessed with its function to write or draw for specific purposes. To be dreaming of working, means you are in need to work to earn money. In your waking life, you may not be earning as much money as you desire. You can either take a more relaxed approach to life, and maybe stop dreaming of working in your sleep. Or you can think of ways to upgrade your economic status. You might want to upgrade your skills to get a better paying job.