What is the origin of 'sleep tight'?
Read moreOne of the mysteries of the English language finally explained.
1A man employed to empty cesspools, outdoor privies, etc., at night and to remove the waste matter. Also figurative. Now archaic and historical.
2A man who works during the night or on a night shift. Also (slang): a nocturnal wrongdoer or criminal; a burglar.
Late 16th century; earliest use found in City of London Book of Fines. From night + man.