All in all this is a wonderful piece, no doubt. As for it's accomplishment of the theme-- I think there is one aspect lacking, which is the hopelessness and circular thought loops of real insomnia, but it is a subjective topic.
What I love about this immensely is it's essence of being a place where, despite being late, I would not sleep. It is dark, it is past my bedtime (perceivably), but this space is so welcoming. It engages the viewer in the lush textures of dawn. The cool, for some depressing, tones of temperature really make it a surreal kind of comfort found in this image. You don't know if this is a comfortable place physically, you just know it is vast, and flourishing, even without you there to witness it.
There could be more focus directed on that reflection of body of water in behind-- I think that, serving as a barrier between the intimidating night sky and the unexpected warmth of the foreground. It is just one solidifying element I can think of.
As for your choice of focal length and rectilinear final outcome, I think you hit the nail on the head. The straightness of the trees in particular enhances the mood significantly.
I would have been tempted to keep in some more details, although the crucial ones are included here. There is clearly a dramatic moment happening in the photo, so dramatic reduction of shadows feels fitting. I like the element of warmth in the tips of the grass and blooming trees, and feel like there could have been just a touch more.
Looks like it was fun to go shoot
keep it up.