We examined the association between salivary mitochondrial DNA (mtDNA) copy number and chronic fatigue combined with depression and insomnia.
This cross-sectional study included 58 healthy adults with moderate to severe fatigue (Brief Fatigue Inventory [BFI] ≥4) for longer than 6 months. Subjects were classified as those without combined symptoms, with either depression (Beck Depression Inventory [BDI] ≥13) or insomnia (Pittsburgh Sleep Quality Index [PSQI] ≥5), or with both depression and insomnia. Salivary mtDNA copy number was measured by real-time quantitative polymerase chain reaction. The association was evaluated using a general linear model.
About 76% of participants had either depression or insomnia as additional symptoms. These subjects were predominately female, drank more alcohol, and exercised less than those without combined symptoms (P<0.05). The group with both depression and insomnia exhibited significantly higher BFI and lower mtDNA copy number than those without combined symptoms (P<0.05). After adjusting for confounding factors, significant negative associations between mtDNA copy number and usual fatigue were found in the group without combined symptoms, whereas the negative associations in the group with combined symptoms were attenuated. BDI and PSQI were not associated with mtDNA copy number.
Chronic fatigue is negatively associated with salivary mtDNA copy number. Salivary mtDNA copy number may be a biological marker of fatigue with or without combined symptoms, indicating that a separate approach is necessary.
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Shift workers are increasing worldwide, and various negative health effects of shift work have been reported. This study aimed to evaluate the relationship between shift work and health behavior.
This cross-sectional study included a total of 11,680 Korean adults (6,061 men and 5,619 women) aged ≥20 years old who participated in the Fifth Korean National Health and Nutrition Examination Survey, 2010–2012. Multiple logistic regression analysis was performed to evaluate the association between shift work and health behavior after adjusting for covariates.
In men, shift work was associated with an increased risk of inadequate sleep (odds ratio [OR], 1.18; 95% confidence interval [CI], 1.00 to 1.40) compared to day work. In women, shift work was associated with an increased risk of smoking (OR, 1.73; 95% CI, 1.34 to 2.22) and inadequate sleep (OR, 1.24; 95% CI, 1.05 to 1.47) compared to day work. In an age-stratified subgroup analysis, female shift workers aged ≥50 years old demonstrated an increased risk of smoking (OR, 5.55; 95% CI, 3.60 to 8.55), alcohol consumption (OR, 2.22; 95% CI, 1.53 to 3.23), and inadequate sleep (OR, 1.50; 95% CI, 1.10 to 2.05) compared to female day workers.
Shift work is associated with worse health behavior, and this is most evident in women aged ≥50 years. Targeted strategies to reduce the negative health effects of shift work should be implemented, with consideration of shift workers' demographic characteristics.
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Alcohol is traditionally known to have a relaxing effect. However, persons who consume alcohol in excessive amounts suffer from poor sleep quality and patients with alcohol use disorders commonly report insomnia. In this study, we aimed to evaluate the effects of alcohol use on sleep quality.
A questionnaire-based cross-sectional survey was conducted with 234 men and 159 women who had visited a general hospital. We used structured questionnaires, including Alcohol Use Disorder Identification Test-Korean revised version (AUDIT-KR) and the Pittsburgh Sleep Quality Index-Korean version (PSQI-K). We analyzed the association between scores for all subcategories of the PSQI-K and the AUDIT-KR and then analyzed the correlation between AUDIT-KR and global PSQI-K scores.
The global PSQI-K score for men was positively correlated with the AUDIT-KR score (P=0.008) after adjusting for age, chronic disease, tobacco use, exercise, depression, and anxiety. The AUDIT-KR score was significantly associated with subjective sleep quality (P=0.005), sleep duration (P=0.047), and sleep disturbance (P=0.048); it was not associated with sleep latency, sleep efficiency, or daytime dysfunction. Sleep disturbances due to snoring were significantly associated with total AUDIT-KR score (P=0.008). There was no correlation between the global PSQI-K and AUDIT-KR scores for women (P=0.333). However, daytime dysfunction showed a significant association with total AUDIT-KR score (P=0.048).
Men with higher AUDIT-KR scores tended to suffer from poor sleep quality. AUDIT-KR scores showed significant correlations with subjective sleep quality, sleep duration, and sleep disturbances in men.
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