This paper examines the neuroanatomical and neurophysiological basis of the frequent fear of darkness. Man is primarily a diurnal animal and his night vision is distinctly inadequate while the mode of life of today calls for a great amount of nocturnal activity. Vision is one of the most accurate of our senses and one of the most heavily taxed in our attempts to orient ourselves within the real world. The suppression of vision promotes both sleep and regression. Night vision is primarily peripheral vision which helps confuse perceptions and fantasies in the dark.