Moral decision-making at night and the impact of night work with blue-enriched white light or warm white light: a counterbalanced crossover study
Creators: name: Sunde, Erlend
name: Harris, Anette
name: Olsen, Olav Kjellevold
name: Pallesen, Ståle
Publisher: name: Taylor & Francis
Year: 2024
Subjects: subject: Neuroscience
subject: Physiology
subject: FOS: Biological sciences
subject: Pharmacology
subject: Biotechnology
subject: Evolutionary Biology
subject: Developmental Biology
subject: Mental Health

description: Cognitive function, including moral decision-making abilities, can be impaired by sleep loss. Blue-enriched light interventions have been shown to ameliorate cognitive impairment during 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 warm white light. Using a counterbalanced crossover design, three consecutive night shifts were performed in blue-enriched white light (7000 K) and warm white light (2500 K) provided by ceiling-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 cognitive schemas depicting different levels of cognitive moral development, was administered. Data from 30 (10 males, average age 23.3 ± 2.9 years) participants were analysed using linear mixed-effects models. Activation of the post-conventional schema (P-score), that is, the most mature moral level, was significantly lower for night work in warm white light (EMM; estimated marginal mean = 44.3, 95% CI = 38.9–49.6; <i>p</i><sup>holm</sup>=.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 reduced for night work overall (EMM = 45.9, 95% CI = 41.1–50.8; <i>p</i>=.008), that is, irrespective of light condition, 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. the lowest moral level) differed significantly between light conditions. The MN-score was however increased for night work overall (EMM = 26.8, 95% CI = 23.1–30.5; <i>p</i>=.033) compared to daytime (EMM = 23.1, 95% CI = 18.9–27.2). The results indicate that moral decisions during simulated night work in warm white light, but not blue-enriched white light, become less mature and principle-oriented, and more rule-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. <i>Trial registration:</i> ClinicalTrials.gov (ID: NCT03203538) Registered: 26/06/2017; https://clinicaltrials.gov/study/NCT03203538 The quality of moral decision-making, seen as the activation of cognitive schemas depicting different levels of moral development, was reduced during simulated night work in warm white light, but not blue-enriched light, compared to daytime.The quality of moral decision-making sems to be reduced during simulated night work, compared to daytime.More studies assessing the impact of night work and light interventions on the quality of moral decision-making are needed to validate these tentative findings. The quality of moral decision-making, seen as the activation of cognitive schemas depicting different levels of moral development, was reduced during simulated night work in warm white light, but not blue-enriched light, compared to daytime. The quality of moral decision-making sems to be reduced during simulated night work, compared to daytime. More studies assessing the impact of night work and light interventions on the quality of moral decision-making are needed to validate these tentative findings.