Common words:
* Nocturnal: Relating to or active at night.
* Nocturne: A piece of music, especially for piano, evoking the atmosphere of night.
* Noctilucent: Shining at night.
* Noctivagant: Wandering at night.
Less common words:
* Noctambulation: The act of sleepwalking.
* Noctambulist: A person who sleepwalks.
* Noctufuge: A person who fears the night.
* Nocturnalism: A preference for being active at night.
* Noctambulant: (adjective) Relating to sleepwalking.
Scientific terms:
* Nocturnal emissions: The involuntary release of semen during sleep (also known as wet dreams).
* Nocturia: Frequent urination at night.
* Nyctalopia: Night blindness.