Have you ever been going over a dream, only to feel really stupid for not noticing a very obvious sign that you were dreaming? Last night I dreamt I was watching the weather report on TV, which for some reason was in French. Anyways, the French lady said that my city was in the middle of a huge snowstorm (that alone should have tipped me off, since it hasn't snowed yet this year). So I decided to look out my window and noticed that the entire sky was gray, and there were these huge hurricane-shaped white spirals in it. It looked very strange, but I just thought "hey, that's pretty cool" and went about my daily business.

Any theories why our reasoning capacities are so dull during normal dreams?