Moral psychology is used to explore the interaction between regulatory mode (locomotion; assessment) and diurnal preference (“early birds”; “night owls”). Moral and immoral behavior was partly explained by an interaction between regulatory mode and the time of day the task took place. In Studies 1a and 1b, we established a relation between self-reported diurnal preference and regulatory mode using both a chronic measure and an induction: stronger locomotion preferring an earlier time of day; stronger assessment preferring a later time of day. In Study 2, we show that those with a locomotion predominance were less likely to invest in a public good later in the day compared to those with an assessment predominance. Lastly, in Study 3, those induced into an assessment mode were more likely to cheat when randomly assigned to complete a task in the morning compared to those induced into a locomotion mode.