Person working when others sleep

Wikipedia Word definitions in Wikipedia
A night owl , evening person or simply owl , is a person who tends to stay up until late at night. The opposite of a night owl is an early bird , a lark as opposed to owl, someone who tends to begin sleeping at a time that is considered early and also wakes ...

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
night owl \night" owl`\ n. A person who likes to be active late at night. Syn: nighthawk, nightbird.

Wiktionary Word definitions in Wiktionary
n. (context idiomatic English) One who stays up late at night or goes to bed late.

WordNet Word definitions in WordNet
n. a person who likes to be active late at night [syn: nighthawk , nightbird ]