I have a wall across from the doorways of a bedroom and "office." It reflects light into the bedroom which bothers people trying to sleep with the other door open. What would be a good way to reduce the light reflection? Ideally we could keep both the doors open to hear each other if needed and also for airflow and pet traffic. Also light in the office is needed for hobby work so simply turning the light off isn't always the best solution, either. Preferably some kind of wall hanging would be what I'm thinking of.
Hang black felt - it eats light quite effectively. You want to make sure that it's fire-treated, or apply a fire treatment yourself, since "things like curtains" (which it would be) are a big problem in spreading fire fast - if not treated to prevent/reduce that issue. Other black (or dark colored) fabrics may work, but the surface on felt is particularly effective at being non-reflective.
You could also apply a flat black/dark paint, but that might not be a viable option (did not specify, but you were asking about "preferably a wall hanging.")
Depending on what the lighting in the office is, and the nature of the hobby work, using directed task lighting rather than a general overhead light may also help reduce light bleed.