You can, but we would not recommend it. If you do, you're going to have soft emulsion around the perimeter of the frame, which can peel the hardened emulsion away or even cause washout issues in the image area (causing unexposed emulsion to run into the image area, and then start to expose again).
If you plan on doing this, you will want to expose, then cover the exposed emulsion with something that can completely block UV rays (example would be to tape a sheet of cardboard to the screen that is a little larger than the image- you would want to do so on each side). You can then put the screen under regular light or use flood lamps to expose the perimeter. Once this is done, you can proceed with final washout. Keep in mind, there's no recommended time for re-exposing the edges to light, you will need to test that out.