Increased digital media use is associated with sleep problems among university students: A study during the COVID-19 pandemic in Japan.

This retrospective cohort study investigates the association between the incidence of sleep problems and changes in digital media use among university students during the COVID-19 pandemic. It used data from annual health check-ups performed at a Japanese university in 2019 and 2020. Students undergoing these check-ups were identified to respond to questions about sleep problems, digital media use, breakfast and exercise habits, and stress. In total, 3,869 students were included in the analysis. The association between the incidence of sleep problems in 2020 and the changes in digital media use between 2019 and 2020 was assessed using logistic regression models. The rate of long digital media use (≥ 2 hours) in 2019 was 42.6%, while in 2020 it was 53.6%. Incidence of sleep problems was observed in 244 students (6.3%) in 2020. There were 786 students (20.3%) who used digital media for ≤ 2 h in 2019 and ≥ 2 h in 2020. From the sample, 66 students (8.4%) reported incidence of sleep problems in 2020. Additionally, those respondents who specifically reported increased digital media use between 2019 and 2020 (increased use) where at greater risk (OR: 1.76; 95% CI: 1.21, 2.55) of reporting sleep problems in 2020, even after controlling for other study variables. Thus, this study provides evidence that the incidence of sleep problems has had a significant association with an increase in digital media use among university students throughout the COVID-19 pandemic. These findings highlight the importance of ensuring appropriate digital media use among students for improved quality of sleep.

Association of weekday-to-weekend sleep differences and stress response among a Japanese working population: a cross-sectional study.

OBJECTIVES: To investigate the relationship between differences in weekday-to-weekend sleep habits and stress responses in a working population. METHODS: This cross-sectional study used data from university workers on sleep habits, differences in sleep duration between weekdays and weekends, and each midpoint of the sleep phase on weekdays and weekends. Social jetlag was defined as the difference in the midpoint of the sleep phase between weekdays and weekends. In addition, the Brief Job Stress Questionnaire assessed stress responses and stress-related factors. To examine sleep-related factors affecting stress responses, regression analysis was performed with adjustments for age, sex, and stress-related factors. RESULTS: Analyzed were 2,739 participants. Sleep duration differences obtained by subtracting sleep duration on weekdays from that on weekends, social jetlag, and weekday sleep duration were significantly associated with an increased risk of stress responses in a univariate linear regression model. Adjusting for age, sex, job stressors, and stressor buffering factors did not change this trend. However, when additionally adjusting for all sleep parameters, only sleep duration differences and weekday sleep duration were significantly associated with stress responses (ß 0.67 [95% CI 0.24, 1.10], p = 0.002), (-0.66 [-1.20, -0.13], p = 0.015). CONCLUSIONS: This study provided further evidence that weekday sleep duration and weekday-to-weekend sleep duration differences were independently associated with stress responses even when considering stress-related factors. However, social jetlag was not clearly associated with stress responses. Our findings highlighted the necessity of securing sufficient sleep for stress management and mental health promotion in a working population.

Discrepant Diagnostic Results of Nested Polymerase Chain Reaction-based Genotyping in a Patient with Hepatitis C Virus and Human Immunodeficiency Virus Coinfection.

Accurate genotyping is important to improve the treatment of hepatitis C virus (HCV) infection. We herein report a 44-year-old Japanese man with hemophilia A and coinfection of HCV and human immunodeficiency virus (HIV) who was diagnosed with HCV genotype 4 by direct sequencing. Two genotyping tests based on the nested polymerase chain reaction method that we used misdiagnosed his genotype as 2b and 1b. Although several HCV genotyping tests are available in Japan, it is important to recognize that some cannot detect genotype 4. Care should be taken when genotyping HCV patients who have received non-heated coagulation factor preparations or were infected abroad.

Potential role of serotonin as a biological reductant associated with copper transportation.

Serotonin (5-HT) is a neurotransmitter that is derived from tryptophan. Owing to a hydroxyl group attached to the indole nucleus, 5-HT exhibits a considerably higher redox activity than tryptophan. To gain insight into the biological relevance of the redox activity of 5-HT, the effect of Cu(I)-binding ligands on the 5-HT-mediated copper reduction was investigated. The d-d transition band of Cu(II) complexed with glycine [Cu(II)-Gly2] was not affected by addition of 5-HT alone but was diminished when a thioether-containing compound coexists with 5-HT. Concomitant with disappearance of the d-d transition band of Cu(II)-Gly2, the π-π* transition band of 5-hydroxyindole of 5-HT exhibits a red-shift which is consistently explained by oxidation of 5-HT and subsequent formation of a dimeric species. The redox reactions between 5-HT and copper are also accelerated by a peptide composed of a methionine (Met)-rich region in the extracellular domain of an integral membrane protein, copper transporter 1 (Ctr1). Since Ctr1 transports copper across the plasma membrane with specificity for Cu(I), reduction of extracellular Cu(II) to Cu(I) is required for copper uptake by Ctr1. Metalloreductases that can donate Cu(I) for Ctr1 have been identified in yeast but not yet been found in mammals. The results of this study indicate that the Met-rich region in the N-terminal extracellular domain of Ctr1 promotes the 5-HT-mediated Cu(II) reduction in order to acquire Cu(I) via a non-enzymatic process.