Association of natural sleep with moral utilitarianism: No evidence from 6 preregistered studies.

Recent research has shown that sleep is associated with moral judgment. Most of these studies have focused on moral awareness and unethical behaviors but far fewer have examined the impact of sleep on moral utilitarianism. We report a set of six preregistered cross-sectional studies which explore the association between moral utilitarianism and sleep quantity and quality at both the acute and chronic levels. A total of 582 participants drawn from diverse populations (USA, UK and France) addressed various measures of sleep quantity, sleep quality, and moral utilitarianism. We report a meta-analysis which showed only a weak association between sleep and moral utilitarianism. Despite the heterogeneity in the samples and methods employed, equivalence tests ruled out the possibility that we missed medium to strong effect sizes. We discuss the implication of these findings in the light of the moral judgment literature.