Shift workers are mostly suffered from the disruption of circadian rhythm and health problems. In this study, we designed proper light environment to maintain stable circadian rhythm, cognitive performance, and mood status of shift workers. We used five-channel light-emitting diodes to build up the dynamic daylight-like light environment. The illuminance, correlated color temperature, and circadian action factor of light were tunable in the ranges of 226 to 678 lx, 2680 to 7314 K, and 0.32 to 0.96 throughout the day (5:30 to 19:40). During the nighttime, these parameters maintained about 200 lx, 2700 K, and 0.32, respectively. In this light environment, three subjects had engaged in shift work for 38 consecutive days. We measured plasma melatonin, activity counts, continuous performance tests, and visual analogue scale on mood to assess the rhythm, cognitive performance, and mood of subjects. After 38-day shift work, the subjects’ peak melatonin concentration increased significantly. Their physiological and behavioral rhythms maintained stable. Their cognitive performance improved significantly after night work, compared with that before night work. Their mood status had no significant change during the 38-day shift work. These results indicated that the light environment was beneficial to maintain circadian rhythm, cognitive performance and mood status during long-term shift work in closed environment.

In this study, red, green, cyan, warm white and cool white (RGCWW) LEDs are individually controlled to simulate dynamic daylight. The spectral power distributions (SPDs) are measured for both the daylight and the mixed white light. The correlated color temperature (CCT), circadian action factor (CAF) curves in the daytime of the mixed white LED almost overlap to those of daylight with a small error of about 1%. The CIE chromaticity coordinates of the mixed white light are distributed along the Planckian locus with a little deviation below 0.003. Also, its color rendering index (CRI) is above 90. The RGCWW five-chip LEDs of high circadian and visual performances will benefit to synchronize circadian rhythm in closed environment during long time without daylight, combined with better mood and alertness. The simulation errors and development trend of the mixed lighting are discussed.

Anxiety is a common disorder among college students, especially those with obesity. Obesity contributes to metabolic disorders and disturbs the neural functions, further leading to anxiety. In this cross-sectional study, we aimed to determine the association between obesity and anxiety among college students and identified the potential factors for obesity-associated anxiety. We evaluated the intervention effects of calorie restriction on anxiety. Self-reported questionnaires were distributed to 1381 college students from January to March in 2021. Anxiety was measured by the State-Trait Anxiety Inventory (STAI). Participants were classified into anxiety and non-anxiety groups according to their STAI scores. Chi-squared test and logistic regression were used to analyze the potential factors. We found that 383 college students exhibited anxiety, accounting for 30.1% among all included college students, which was higher than the global average. The association between anxiety and obesity was observed among college students (p = 0.009), especially in males (p = 0.007). We identified that pre-obesity (p = 0.012), unhealthy calorie intake (p = 0.001), dieting (p = 0.003) and high academic year (p = 0.006) as the risk factors for anxiety and found that the long sleep duration was a protective factor for anxiety (p < 0.001). We found that more obese students showed an improvement of anxiety than the underweight students after calorie restriction (p < 0.001). Collectively, our findings suggest that obesity-associated anxiety is prevalent among the college students and could be alleviated by moderate calorie restriction. It is necessary for students to receive anxiety management in their college life. Additionally, the proper calorie restriction should be promoted to help students protect against obesity and obesity-associated anxiety.

Introduction Major depressive disorder (MDD) is a leading cause of disability among adolescents, yet available treatments remain limited. Bright light therapy (BLT) is a non-pharmacological intervention with demonstrated efficacy in adults. However, its clinical utility and underlying neural mechanisms in adolescents remain unclear. This trial aims to evaluate the clinical efficacy, time to onset, safety and applicability of home-based BLT in outpatient adolescents with MDD, and to explore its underlying neural mechanisms using functional near-infrared spectroscopy (fNIRS). Methods and analysis This is a randomised, placebo-controlled, three-arm multicentre clinical trial. A total of 126 outpatient adolescents aged 13–17 years with MDD will be randomly assigned to receive high-intensity BLT, medium-intensity BLT or placebo dim red light using a portable light box in a home-based setting for 40 min each morning over 4 weeks, followed by a 2-week follow-up. 42 age-matched and gender-matched healthy controls will also be enrolled for baseline assessments only, serving as normative references for comparison. The primary outcome will be the change in total scores on the 17-item Hamilton Rating Scale for Depression from baseline to week 4. All analyses will follow an intention-to-treat framework to ensure methodological rigour. The primary outcome will be analysed using analysis of covariance and linear mixed-effects models. Secondary outcomes will include response and remission rates, time to onset, maintenance of efficacy, self-reported depressive symptoms, sleep quality, cognitive function, anxiety, irritability, suicidal ideation, non-suicidal self-injury, self-efficacy and the overall safety profile of BLT. Prefrontal cortical activity will be measured using fNIRS at baseline and week 4 to explore potential neural mechanisms. Approximately 15% of participants will additionally take part in a qualitative substudy exploring experiences and acceptability of BLT. Ethics and dissemination The study protocol has been approved by the Ethics Committee of Peking University Sixth Hospital (approval number: 2025–24). Written informed consent will be obtained from all participants and their legal guardians prior to enrolment. Study findings will be disseminated through peer-reviewed journals and conference presentations. Trial registration number NCT06913309.