It could be atelectasis, a partial collapse of the lung. It can happen when you can't take a deep breath in, and it can happen while sleeping when breathing muscles are weaker.

Do you have a copy of the report?

Try sleeping in a recliner or other chair to see if it helps. It could also be inflammation from lupus, which won't show up on regular Xray. But you did have a CT. Sometimes it only shows up on MRI.

Have they decided if you have lupus?

Try to address the underlying inflammation and/or weakness and see if that improves it.

I hope that helps.

Annie