Two types of False Awakenings that I always get

Ever since I started with lucid dreaming about two years ago all my lucids (20 so far) have started out as False Awakenings, although I always recognize them and become aware.
These are the two types, and my own names for them:

"Dark Lucidity"
My room is very dark, but I have full vision

"Bright Lucidity"
Extremely vivid and in daylight, but I am blind on my left eye and can only partially see anything with my right eye

In both of these dreams I move pretty slowly, perhaps 25% as fast as in real life, and even though I know I am dreaming I am still almost on auto-pilot and can't think clearly, and I also have problems talking.
I did once manage to play around in Bright Lucidity and that made my week, but except for that time these dreams always end way too quickly; I think they last for about 2 minutes on average .

Now, I have two questions:

*why do all my lucid dreams begin as these specific types of False Awakenings?
*how can I make them last longer?

Most of my lucid dreams start as false awakenings as well, as for reason why we have lucid dreams often start like that, is that i think we have much higher awareness in dream during false awakenings and when we practice lucid dreaming we learn to easily turn them into lucid dreams, thus if we have many of them, we'll get lucid from the most of time. :-?
As for dreams lasting longer, you might want to look into stabilization techniques to stabilize the lucid dream when it starts or when it starts fading out, here's tutorial: Dream Stabilization and Clarity Tutorial - Lucid Dreaming - Dream Views . ;)