That's quite interesting, I don't think I've heard of that happening before! At this point, I wouldn't mind it, to be honest.Never could get to sleep before 2-4A, and could sleep through any alarm clock for hours. Some point in my later 30's it suddenly flipped - have a really had time staying up past 10 or so, and I always wake up around 5:30A. Don't know what it suddenly change. Perhaps getting away from the constant Seattle grey mornings helped.
Cloudy weather also affects me negatively. I am very lucky to live somewhere that is sunny 75% of the time. The past week has been the typical "May gray, June gloom" that happens every year, and I certainly have felt it.