Chronotype

Chronotype is an individual's biological propensity toward being more active and alert at certain times of day — morning-type ("lark"), evening-type ("owl"), or intermediate. It is substantially genetic and shifts predictably with age.

Misalignment between your chronotype and your schedule (social jetlag) correlates with worse sleep, mood and metabolic outcomes. Adolescents shift toward eveningness; most adults drift back toward morningness after 30.