Nocturnality is a behavior in some non-human animals characterized by being active during the night and sleeping during the day. The common adjective is nocturnal, with diurnal meaning the opposite.
Owls are well known for being nocturnal, but some owls are active during the day.
The kiwi is a family of nocturnal birds endemic to New Zealand.
The honey badger, a nocturnal animal.
Light pollution on a ski slope in Finland gives the area a hazy, brightened sky.