Chun MY. Korean J Fam Med. 2012 May;33(3):144-151. http://dx.doi.org/10.4082/kjfm.2012.33.3.144

Both extremely long and short sleep durations have been associated with increased risk of numerous health problems. This study examined the association between self-reported sleep duration and reporting of musculoskeletal pain in the adult Korean population. This study included data from 17,108 adults aged ≥50 years, obtained from the Korea National Health and Nutrition Examination Survey 2010–2012 and 2013–2015. Self-reported daily hours slept and the presence of musculoskeletal pain in knee joint, hip joint, or low back were examined. Patients were stratified into 5 groups by their sleep duration: ≤5, 6, 7, 8, or ≥9 h. Multivariate logistic regression analysis was performed, adjusting for covariates including age, sex, marital status, smoking, alcohol use, family income level, education, physical exercise, body mass index (BMI), and stress level. A U-shaped relationship was observed between the length of sleep duration and the presence of musculoskeletal pain. After adjusting for covariates, sleep duration of ≤5 h or ≥9 h was significantly associated with musculoskeletal pain experienced for more than 30 days over a 3-month period. We also found that the presence of multi-site musculoskeletal pain was significantly higher among those who slept for ≤5 h or ≥9 h than in those who slept for 7 h. These findings suggest that either short or long sleep duration is associated with musculoskeletal pain among Korean adults.

As the smartphone has become an indispensable device in modern lives, consequential psychosocial problems such as smartphone addiction have been getting attention worldwide, especially regarding adolescents. Based on its positive effect on young individuals’ mental health, mind subtraction meditation has been widely applied to many school-based programs in South Korea. This study aims to identify the effects of a school program based on mind subtraction on the smartphone addiction of adolescents. A total of 49 high school sophomores, 24 from the experimental group (mean age = 16), and 25 from the control group (mean age = 16) are included in this case-control study. The experimental group is given the meditation program sessions in the morning, two times a week for 20 min per session, for a total of 12 weeks. The experimental group shows improvements regarding the ‘smartphone addiction’ section (p < 0.001), for instant satisfaction (p < 0.001) and long-term satisfaction (p < 0.001). Concerning the ‘self-control’ section and decreasing stress (p < 0.001), problem focusing (p < 0.001), and social support navigation (p = 0.018), there are improvements in these ‘stress coping strategies’ sections. This study directly shows the positive effect of mind subtraction meditation on smartphone addiction in adolescents and, thus, provides guidance to the future development of smartphone addiction prevention programs for young individuals.

The importance of sleep has been gaining more and more attention nowadays. It has been widely studied that some major health issues, such as cardiovascular diseases or mortality, are closely related to the extreme ends of sleep durations. Anemia is one of the health problems in modern society. In this study, we aimed to find a relationship between anemia occurrence and sleep duration. Data of 11,131 Korean adults aged 19 years or older were recruited from the 2016–2017 Korea National Health and Nutrition Examination Survey and analyzed in this cross-sectional study. ‘Anemia’ was defined in this study by hemoglobin level of <13 g/dL in men and <12 g/dL in women. Selected data were sorted into five groups by sleep duration: <5 h, 5 h ~ <6 h, 6 h ~ <8 h, 8 h ~ <9 h, and ≥9 h per day. We performed multivariate logistic regression analysis to assess the relationship between sleep duration and risk of anemia after adjusting for covariates including age, gender, family income level, education level, physical activity, cigarette smoking, and alcohol usage. Other factors were assessed in the analysis, such as depression, hypertension, diabetes, dyslipidemia, stroke, coronary artery disease, malignancy, stress level, and body mass index (BMI). We found that sleep duration of <5 h was related to high risk of anemia (odds ratio = 1.87; 95% confidence interval = 1.01–3.49, sleep duration of 6 h ~ <8 h as the reference group). Also, sleep duration of ≥9 h was related to lower risk of anemia in most premenopausal women after adjusting for covariates (odds ratio = 0.61; 95% confidence interval = 0.38–0.96, sleep duration of 6 h ~ < 8 h as the reference group). Male individuals with sleep durations of <5 h (odds ratio = 2.01; 95% confidence interval =1.05–3.84) and of ≥9 h (odds ratio = 2.48; 95% confidence interval =1.63–3.81) had a significantly higher risk of anemia without covariate adjustment. Postmenopausal women with sleep durations of ≥9 h had a significantly higher risk of anemia (odds ratio =2.02; 95% confidence interval =1.33–3.08) without adjusting for covariates. However, the associations became statistically insignificant after adjusting for age and covariates in both men and postmenopausal women. In conclusion, we found significant associations between extreme ends of sleep duration and risk of anemia in premenopausal Korean women. However, we did not observe strong associations between self-reported sleep duration and anemia risk in men or postmenopausal women.

Orientation selectivity is a remarkable feature of the neurons located in the primary visual cortex. Provided that the visual neurons acquire orientation selectivity through activity-dependent Hebbian learning, the development process could be understood as a kind of symmetry breaking phenomenon in the view of physics. The key mechanisms of the development process are examined here in a neural system. Found is that there are at least two different mechanisms which lead to the development of orientation selectivity through breaking the radial symmetry in receptive fields. The first, a simultaneous symmetry breaking mechanism, bases on the competition between neighboring neurons, and the second, a spontaneous one, bases on the nonlinearity in interactions. It turns out that only the second mechanism leads to the formation of a columnar pattern which characteristics accord with those observed in an animal experiment

Chun MY. Korean J Community Nutr. 2015 Aug;20(4):281-290. http://dx.doi.org/10.5720/kjcn.2015.20.4.281