Nocturnality's an animal behavior characterized by being active during the night and sleeping during the day. The opposite, diurnality,'s associated with human lifestyle and most familiar animal species. The intermediate crepuscular schedule (twilight activity)'s also common. Some species are active both during the day and night. Living at night can be seen as a form of niche differentiation, where a species' niche's partitioned not by resources but by time itself, for example temporal division… (More on Nocturnality)