Depression and suicidal ideation among Chinese college students during the COVID-19 pandemic: the mediating roles of chronotype and sleep quality.

BACKGROUND: This study was intended to investigate the correlation between depression and suicidal ideation among Chinese college students during the COVID-19 pandemic and the potential mediating roles of chronotype and sleep quality in this relationship . METHODS: A sample of 4,768 college students was selected from four institutions in Anhui Province, China, and the study was conducted during the COVID-19 pandemic (November to December 2020) using a stratified, cluster, multi-stage sampling method. This study used the two-item Patient Health Questionnaire (PHQ-2) to assess depressive symptoms, the Morningness-Eveningness Questionnaire 19 (MEQ-19) to determine individual sleep chronotypes (i.e., morning or evening preference), and the Pittsburgh Sleep Quality Index (PSQI) to evaluate sleep quality. Participants were asked about suicidal ideation. MPLUS 8.3 software was used to analyze the mediating effect of chronotype and sleep quality on the relationship between depression and suicidal ideation. RESULTS: During the COVID-19 pandemic, the prevalence of suicidal ideation among Chinese college students was 5.4%. Depression was inversely correlated with chronotype (beta = - 0.346, P < 0.01) and positively correlated with sleep quality (beta = 0.846, P < 0.001), indicating that students experiencing depressive symptoms were more likely to have a later chronotype and poor sleep quality. A later chronotype (beta = - 0.019, P < 0.05) and poor sleep quality (beta = 0.066, P < 0.01) predicted suicidal ideation. Depression emerged as a direct and significant risk factor for suicidal ideation (effect value = 0.535, 95% confidence interval: 0.449 ~ 0.622). Chronotype and sleep quality were found to have potential mediating effects on the relationship between depression and suicidal ideation; however, the chain-mediating effect of chronotype and sleep quality was not statistically significant. CONCLUSIONS: Our findings suggest that during the COVID-19 pandemic, depression can precipitate suicidal ideation through its influence on sleep chronotype and quality. These compelling findings highlight the urgency of early intervention strategies intended to mitigate suicidal thoughts, particularly among students exhibiting depressive symptoms, who experience disrupted sleep patterns and poor sleep quality.

Association of learning environment and self-directed learning ability among nursing undergraduates: a cross-sectional study using canonical correlation analysis.

OBJECTIVES: This study explores the relationship between the perception of the learning environment and self-directed learning (SDL) ability among nursing undergraduates. DESIGN, SETTING AND PARTICIPANTS: A cross-sectional study was conducted in December 2020 with 1096 junior and senior undergraduate nursing students (aged 16-22) from Wannan Medical College in Anhui Province, China. OUTCOME MEASURES: The Chinese version of the Dundee Ready Educational Environment Measure questionnaire and a validated Chinese version of college students' SDL ability scale were used to assess students' perceptions about their learning environment and their SDL ability. Canonical correlation analysis was performed to evaluate their correlation. RESULTS: The total score for the learning environment was 120.60 (scoring rate: 60.30%), and the score for SDL ability was 89.25 (scoring rate: 63.75%). Analysis indicated that the first canonical correlation coefficient was 0.701 and the contribution rate was 94.26%. The perception of the learning environment was mainly determined by students' perception of learning (SPL) and academic self-perceptions (SASP), with SDL ability mainly determined by self-management ability and cooperative learning ability. SPL and SASP were positively correlated with self-management ability and cooperative learning ability. Multiple linear regression analysis revealed that SPL, SASP, students' perceptions of atmosphere and students' social self-perceptions had a significant impact on SDL ability. CONCLUSIONS: The SDL ability of nursing undergraduates was not high. SPL and SASP were positively correlated with self-management ability and cooperative learning ability. Nursing educators can improve students' SDL ability by changing their learning environment, using, for example, new student-centred teaching methods.

Sulforaphane protects MLE-12 lung epithelial cells against oxidative damage caused by ambient air particulate matter.

Ambient air particulate matter with aerodynamic diameters ≤2.5 µm (PM2.5) can cause pulmonary injury. Oxidative stress is thought to be an important mechanism of PM2.5-mediated toxicity. Sulforaphane (SFN), a compound derived from cruciferous vegetables, is a well-known potent antioxidant; however, its protective effect on lung epithelial cells exposed to PM2.5 is unclear. The results showed that SFN pre-treatment markedly inhibited PM2.5-induced apoptosis of the type II alveolar epithelial cell line MLE-12 by elevating glutathione S-transferase levels and decreasing reactive oxygen species. SFN pre-treatment down-regulated the expression of the pro-apoptotic proteins Bax and Bad, and reduced the activity of caspase-3, while it up-regulated the expression of the anti-apoptotic protein Bcl-2. Moreover, SFN induced the activation of the Akt and ERK pathways, and up-regulated the expression of Nrf2 and its downstream antioxidant genes NQO-1 and HO-1. This is the first study to demonstrate that SFN could protect MLE-12 cells against PM2.5-induced oxidative damage via activation of the Nrf2 pathway and inhibition of the mitochondrial apoptotic pathway; therefore, SFN may be a promising compound for preventing PM2.5-triggered pulmonary cell damage.