One of the fundamental mechanisms of a saccadic automation - rapid eye movement committed involuntarily. With their help, brain scans the environment, putting everything into a single image. When looking at the homogeneous surface, devoid of the field of view of any elements (concrete slabs, asphalt), the brain is trying to collect a puzzle from hundreds of identical pieces, the number of saccades increases, but look nothing to engage, disrupted binocular device and convergence, which results in to a sense of visual discomfort. The same is observed when considering the aggressive video field with a lot of the same elements (skyscrapers with lots of windows) - begins to ripple in the eyes, get on your nerves, and the processes in the brain resemble an epileptic fit.
That's why most comfortable is the natural visual environment - forest, river, or running across the sky, and a variety of decorative elements in the architecture or the calming effect is said to be "pleasing to the eye." Today the sleeping areas do not appear to be tempted to wonder ugly boxes, and huge glass skyscrapers fields are depressing.
These issues are dealt with videoecology - science has developed in Russia in the late twentieth century.