Oh I had somewhat the same problem, always dark outside, but I manage to change it now, or at least the last time I tried, but i have had many dark dreams. 
It seems to be pretty common. I myself have not have much luck changing a dark dream into a bright one. But more common than a dark dream is a cloudy day or twilight dream. Maybe it’s because I see the best in that light normally. I always though of myself as cat like but I didn’t expect to sharethat particular trait with them.