When you are depressed, your concentration can really suffer and you maybe don't pay much attention to what's going on around you. The brain still takes in all the usual information from the real world, it just doesn't try to make any sense of it all. That way one day seems very much like the next. So maybe when you think your mom came in it is because you are remembering a different night not last night.

Thunder Bow is right, dreams are just our mind processing all the experiences of the previous day. When one day is as tedious as the next, our dreams can become part of that tedium.

Not being able to concentrate properly and not being able to form accurate recollections is pretty usual when depressed, so it isn't anything to worry about, but Labor's idea of writng down your dreams is a pretty good idea and will help alleviate some of the confusion.