I've experienced this "is it just morning daydreaming" doubt several times. A couple nights ago, I decided to try just going with it. I though to myself "ok maybe it's a daydream, but maybe a daydream can be like a real dream". I started being aware and critical of the daydream. I tried to observe details and reach out and touch things. Suddenly, it seemed that the daydream turned into a real dream. It's like a 2D image turned into a 3D environment. The dream faded after a few seconds, but it was promising.