nighttime

The hours of darkness between sunset and sunrise; the night.

Nighttime fell like the opening / In the final act of the beginning of time

Smith Barney, for example, goes so far as to shift the hours during which taxi rides home are expensable as nighttime lengthens and shortens, says Moszkowski.

Pertaining to nighttime; appropriate to the night.

Happening during the night.

Discourage nighttime prowlers by installing motion-sensitive lights.