The Morality of Larks and Owls: Unethical Behavior Depends on Chronotype as Well as Time-of-Day

Abstract

The recently-documented “morning morality effect” indicates that people act most ethically in the morning because their energy wanes with the day. An estimated 40% of the population, however, experience increased energy levels later in the day. These “evening people,” we propose, should not show the morning morality effect. Instead, they should show the same or an increasing propensity toward ethicality in the evening. Two experiments supported this hypothesis, showing that people with a morning chronotype tend to behave more ethically in the morning than the evening, while people with an evening chronotype tend to behave more ethically in the evening than the morning. Thus, understanding when people will behave unethically may require an appreciation of both the person (chronotype) and the situation (time-of-day): a chronotype morality effect.

Keywords: circadian rhythm, cognitive processes, morality, ethics, sleep