"Night owl" people are people that stay up real late at night, maybe even all night. I used to be one.
I'm a night owl as well. I sleep better during the day. I have always been an insomniac.
Night owl (person)
A night owl, evening person or simply owl, is a person who tends to stay up until late at night, or the early hours of the morning. Night owls who are involuntarily unable to fall asleep for several hours after a normal time may have delayed sleep phase syndrome. 
The opposite of a night owl is an early bird – a lark as opposed to an owl – which is someone who tends to begin sleeping at a time that is considered early and also wakes early.
owls from their traditional nesting sites in buildings.
In culture.
The tawny owl, like its relatives, has often been seen as an omen of bad luck; William Shakespeare used it as such in "Julius Caesar" (Act 1 Scene 3): "And yesterday the bird of night did sit/ Even at noon-day upon the market-place/ Hooting and shrieking." John Ruskin is quoted as saying "Whatever wise people may say of them, I at least have found the owl's cry always