In a study involving 35 young adults, blue-enriched light was associated with a slightly decreased tendency to endorse negative self-descriptors. A drift diffusion model suggested that this effect may arise from a faster accumulation of evidence when rejecting negative descriptors under blue-enriched light. However, the effect size is small and the study does not control for menstrual cycle effects on mood regulation.

The authors disclose that two of them are investigators on projects related to alertness, safety, and productivity, and have received research funding or acted as consultants for several lighting companies. Two are co-directors and co-founders of Circadian Health Innovations PTY LTD. One has also received research funding from Beacon Lighting and consulted for Dyson. The authors have a vested interest in positive outcomes related to lighting interventions.

While the study is on humans, it does not control for menstrual cycle effects on mood, which could be a significant confound. Also, the sample size is not huge and primarily involves university students (not that representative). While intriguing, the effect size is small and it relies on model fitting which simplifies the complexity of the task. Some authors have COI due to affiliations with related companies. Thus, the methodological limitations and conflict of interest justify the rating.