There’s a growing body of evidence that suggests it’s society, not night owls like Carter, that is wrong. The field of chronobiology seeks to understand how individuals are driven by an internal clock – their “chronotype” – one that is set by genetics, not willpower. The term night owl is shorthand for the chronotype that drives people to go to bed later and rise later. This contrasts with morning larks, who naturally want to go to bed early and wake up early. Most people fall somewhere between the two, with an average sleep cycle running from around 11.30pm until 7.30am. People tend to change over their lifetime. They are larks in childhood, night owls as teens, and more lark-like again as they get older.
Source: Extreme night owls: ‘I can’t tell anyone what time I go to bed’ | Life and style | The Guardian