My sewing machine faces a north facing window but it is set back about 20 inches away from the glass and the window is well-shaded from outside. I've been sewing there for many years and have never had a problem. My machine is fine but I never leave fabric in the machine anyway so I don't know about that. I do know that sunlight will bleach fabric over time. Even in a well-lit room away from windows it's important to re-fold fabric from time to time or keep it covered. Otherwise, you find yourself cutting around bleached out strips. (Been there.)