Moral decision-making at night and the impact of night work with blue-enriched white light or warm white light: a counterbalanced crossover study

Abstract

Background: Cognitive function, including moral decision-making abilities, can be impaired bysleep loss. Blue-enriched light interventions have been shown to ameliorate cognitive impairmentduring night work. this study investigated whether the quality of moral decision-making during simulated night work differed for night work in blue-enriched white light, compared to warmwhite light. Methods: Using a counterbalanced crossover design, three consecutive night shifts wereperformed in blue-enriched white light (7000 K) and warm white light (2500 K) provided byceiling-mounted leD luminaires (photopic illuminance: ~200 lx). at 03:30 h on the second shift (i.e.twice) and at daytime (rested), the Defining issues test-2, assessing the activation of cognitiveschemas depicting different levels of cognitive moral development, was administered. Data from30 (10 males, average age 23.3 ± 2.9 years) participants were analysed using linear mixed-effectsmodels. Results: Activation of the post-conventional schema (P-score), that is, the most mature morallevel, was significantly lower for night work in warm white light (eMM; estimated marginal mean= 44.3, 95% ci = 38.9–49.6; pholm=.007), but not blue-enriched white light (eMM = 47.5, 95% ci =42.2–52.8), compared to daytime (eMM = 51.2, 95% ci = 45.9–56.5). also, the P-score was reducedfor night work overall (eMM = 45.9, 95% ci = 41.1–50.8; p=.008), that is, irrespective of lightcondition, compared to daytime. Neither activation of the maintaining norms schema (MN-score),that is, moderately developed moral level, nor activation of the personal interest schema (i.e. thelowest moral level) differed significantly between light conditions. the MN-score was howeverincreased for night work overall (eMM = 26.8, 95% ci = 23.1–30.5; p=.033) compared to daytime(eMM = 23.1, 95% ci = 18.9–27.2).Conclusion: the results indicate that moral decisions during simulated night work in warm whitelight, but not blue-enriched white light, become less mature and principle-oriented, and morerule-based compared to daytime, hence blue-enriched white light may function as a moderator. Further studies are needed, and the findings should be tentatively considered

Moral decision-making at night and the impact of night work with blue-enriched white light or warm white light: a counterbalanced crossover study