• Journal of Korean Academy of Nursing
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• v.40 no.1
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• pp.43-51
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• 2010

Purpose: The purpose of this study was to investigate sleep habits, sleep disturbance, and circadian types, and to identify factors influencing sleep disturbance in nursing students. Methods: Participants were 140 senior nursing students. The data were collected from May 19 to 27, 2008 using self-report questionnaires. Results: 1) Evening type delayed sleep-wake schedules were more frequent than for morning type, especially during weekend and evening shift duty. 2) In total sleep time, there were no significant statistical differences between morning type and evening type during weekdays, weekend, day or evening shift duty. 3) On weekdays and day shift duty, the mean score for sleep disturbance was significantly higher in the evening type compared to the morning type. 4) Sleep disturbance in weekday and day shift duty was influenced by circadian types, eating habits, and gender. Conclusion: The circadian types are a very important factor for determining the sleep quantity and quality in nursing students.

• Fashion & Textile Research Journal
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• v.5 no.1
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• pp.77-81
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• 2003

The purpose of this study was to investigate the effect of multi-functional fabric on EEG and growth hormone (GH) during sleep and quality of sleep with the 9 young female athletes. The subjects participated in separated experimental procedure; sleeping in multi-functional fabric wear (experimental group) and cotton wear (control group) for 450min. During the night (22:00-05:30), we recorded the changes of nocturnal polysomnographic sleep recording and GH were measured every 60min. The results show that there are significant differences in percentage of stage 1, 2 and slow wave sleep (SWS) between two groups(S1, p<.05; S2, SWS, p<.01). The SWS percentage of experimental group is 1.89 times higher than control group. The changes of GH secretion varied depending on two experimental procedures. The peak of GH secretion in experimental group is more than controls by 2.4time (p<.001). The quality of sleep in experimetal group is significantly higher than control (p<.01). These results suggest muti-functional fabric wear is effective in inducing the deep sleep and increasing GH and quality of sleep.

• Korean Journal of Occupational Health Nursing
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• v.23 no.4
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• pp.235-244
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• 2014

Purpose: The purpose of this study was to identify quality of sleep and its influencing factor among middle-aged male workers. Methods: The subjects of this study were 411 middle-aged male workers living in Seoul and Gyeonggi-do. The data were based from self-reported using structured questionnaires asking about low urinary tract symptoms, circadian rhythm, quality of life and sleep quality including general characteristics. The data were collected from September 11 to October 31, 2013 and analyzed by t-test, one-way ANOVA, Pearson correlation coefficient and hierarchical regression. Results: Mean score of the sleep quality was $5.03{\pm}2.57$ (range: 0~21) and reported as bad sleep quality in 55.7%. Low urinary tract symptoms (${\beta}$=.30, p<.001), circadian rhythm (${\beta}$=-.17, p<.001), quality of life (${\beta}$=-.14, p<.001) were shown as significant association of sleep quality. Conclusion: Strategies to improve sleep quality in middle-aged male workers are necessary and nursing intervention should be developed to improve education program for prevention and management of low urinary tract symptoms. It is also necessary to legalize the institutional devices to upgrade work environment and to place regulations on overtime at work places in order for these workers to obtain sufficient sleep time for recovery of biological rhythms and improving sleep quality.

• The Journal of Pediatrics of Korean Medicine
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• v.35 no.4
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• pp.75-81
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• 2021

Objectives The purpose of this study is understanding the trend of clinical researches on the correlation between precocious puberty and sleep. Methods 18 papers were searched by using keywords 'Precious publicity' and 'Sleep' in Pubmed, China National Knowledge Infrastructure, and those were analyzed for this study. Results Children aged 6 to 18 were participated in longitudinal studies and questionnaire surveys. Hormone levels and EEG were also measured in those children. This study had placed emphasis on the sleeping time and sleep quality, and sex hormones secretion during sleep and changes in the hormone secretion related to the sleep cycles. Historically, oriental medicine studies have demonstrated that there were correlations between precocious puberty and sleep. There are studies from China showed the importance of lifestyle management in preventing and treating precocious puberty, especially with light exposure during sleep. Conclusions Sleep is closely correlated with precocious puberty and it is an important factor to be considered in the prevention and treatment of precocious puberty.

• Sleep Medicine and Psychophysiology
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• v.6 no.2
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• pp.116-125
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• 1999

Objectives: The purpose of this study is to investigate the effect of exercise load on sleep structure and stress hormone secretion during sleep. Methods: Five male physical education students were included in this study after giving their written, informed consents in the Research Institute for Sports Science at the University of Hanyang. All subjects have performed for at least 3 years in a regular aerobic exercises such as football, basketball, and running. The subjects were divided into three groups ; NOE(non-exercise), MDE(middle duration exercise), LDE(long duration excercise). MDE group maintained a total of 120 min exercise, and LDE group maintained a total of 300 min exercise by football, basketball or badminton. All subjects were acclimatized to the experimental sleep condition by spending one night under expermental conditions, including the placement of an intravenous catheter. During the subsequent night(24:00-08:00), somnopolygraphic sleep recordings were obtained, and blood for measuring growth hormone, cortisol, testosterone, and $\beta$-endorphin was collected every 120 min throughout the night. Blood samples were obtained from prominent forearm veins of subjects. Then, the samples were immediately placed in ice and centrifuged within 10 min at 3000 rpm at $4^{\circ}C$. Statistical analyses were performed using the SPSS/$PC^+$. Data were analyzed by one-way ANOVA with repeated measures. Results: No significant differences among groups were observed in sleep latency, total sleep time, stage 2 sleep, and slow wave sleep. However, daytime exercise produced significant changes in stage 1 sleep, REM sleep, stage 2 sleep latency, REM sleep latency and sleep efficiency. Stage 1 sleep, stage 2 sleep latency, and REM sleep latency significantly increased in LDE compared to those of NOE and MDE groups. But the amount of REM sleep significantly decreased in LDE. Sleep efficiency of MDE was higher than those of NOE and LDE. The blood concentrations of growth hormone, testosterone, and cortisol during night sleep were significantly lower in LDE than in NOE. $\beta$-endorphin concentrations in blood during night sleep were not different among groups. Conclusion: The daytime exercise load was significantly related to sleep structure and stress hormone secretion during night sleep. Long duration exercise showed a harmful effect on sleep structure and hormone secretion. However, middle duration exercise had a beneficial effect on sleep structure and hormone secretion during sleep.

• Korean Journal of Biological Psychiatry
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• v.28 no.2
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• pp.58-69
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• 2021

Objectives The aim of this study was to examine the association between the sleep pattern, chronotype (midpoint of sleep on free days) and the depressive symptoms in adults aged 19 years and over in Korea. This study also investigated the mediating effect of perceived usual stress (PUS) and self-rated health (SRH) on the association between chronotype and depressive symptoms. Methods Among the subjects of the 7th Korea National Health and Nutrition Examination Survey (KNHANES) 2016 and 2018, 16142 adults aged 19 or over responded to the survey and finally 8604 were analyzed according to the exclusion conditions. Logistic regression analysis was conducted to see the risk of depressive symptoms, suicidal ideation over sleep pattern, chronotype. Finally, mediation analysis was performed in order to clarify how PUS and SRH are associated to chronoytpe and depression. Results After controlling for potential covariates, weekly sleep duration < 5 hours, ≥ 10 hours was associated with depressive symptoms. And late bed time sleeping after am 1:00 and later midpoints of sleep was associated with a higher level of depressive symptoms. Additionally, the PUS and SRH between chronotype and depressive symptoms showed a serial multiple mediation effect. Conclusions Short or long sleep duration, late bed time and later midpoints of sleep on free days are associated with depressive symptoms. Furthermore, the mechanism between chronotype and depressive symptoms needs to be further clarified by identifying the serial multiple mediation effects of PUS and SRH.

• Journal of Preventive Medicine and Public Health
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• v.56 no.1
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• pp.59-66
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• 2023

Objectives: The aim of this study was to evaluate the effect of body weight status and sleep duration on the discrete-time hazard of menarche in Korean schoolgirls using multiple-point prospective panel data. Methods: The study included 914 girls in the 2010 Korean Children and Youth Panel Study who were in the elementary first-grader panel from 2010 until 2016. We used a Gompertz regression model to estimate the effects of weight status based on age-specific and sex-specific body mass index (BMI) percentile and sleep duration on an early schoolchild's conditional probability of menarche during a given time interval using general health condition and annual household income as covariates. Results: Gompertz regression of time to menarche data collected from the Korean Children and Youth Panel Study 2010 suggested that being overweight or sleeping less than the recommended duration was related to an increased hazard of menarche compared to being average weight and sleeping 9 hours to 11 hours, by 1.63 times and 1.38 times, respectively, while other covariates were fixed. In contrast, being underweight was associated with a 66% lower discrete-time hazard of menarche. Conclusions: Weight status based on BMI percentiles and sleep duration in the early school years affect the hazard of menarche.

• Journal of Sasang Constitutional Medicine
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• v.30 no.1
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• pp.24-31
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• 2018

Objectives The purpose of this study is to find out whether there is any difference in lifestyle by health status in the same Sasang constitution type, and whether there is any difference in lifestyle by the Sasang constitution type in the same health condition. Methods We used collected the clinical data of Korean medicine Data Center (KDC). In this study, we used items of the lifestyle about meal and sleep (Meal regularity, Meal amount, Meal time, Dream, Sleep well, Hard to fall asleep, Shallow sleep, Nap, Sleep time, Quality of sleep) as variables. We found the differences of lifestyles using the Chi-square test and ANOVA. We analyzed using SPSS statistics 21.0 for Korean. Results & Conclusions When we compared the lifestyle by Sasang constitution type in each health status, there were differences in items of meal amount and nap. When we compared the lifestyle by health status in each Sasang constitution type, we found differences in items of meal regularity, sleep well, nap etc. However, in TE tpe, there was not these differences by health status.

• Journal of the Ergonomics Society of Korea
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• v.19 no.3
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• pp.1-12
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• 2000

The Korean version of the morningness-eveningness questionnaire (MEQ) and sleep habits inventory were administered to 1,038 Korean male daytime workers and were analyzed according to age and chronotype to determine what these factors reveal about sleep habits in view of phase difference of circadian rhythm. The mean and distribution of scores on the MEQ moved significantly toward the morning type with aging. Bedtimes and waking times were progressively later from the morning, intermediate, to evening types, and were also earlier with aging. Preferred bedtimes and waking times showed more distinct differences than did the habitual times in each chronotype. The percentage of subjects who answered that sleep length was 'short', mood upon waking was 'bad', and variabilities of bedtime and sleep length were 'large' were greater in the young and evening types than in the elder and morning types, respectively. These findings suggested that subjects were shifted toward the morning type and the phase of circadian rhythm had moved forward with aging. Preferred bedtime and waking time were a better reflection of individual circadian rhythms than habitual bedtime and waking time.

• Korean Parent-Child Health Journal
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• v.3 no.1
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• pp.60-72
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• 2000

Studies are needed to determine the standard norms for sleep/activity patterns in new born baby and there have been no established reports of discrepancy of sleep/activity patterns in new born baby among various races. The purpose of this study is to determine whether the NCASA(Nursing Child Assessment Sleep Activity Record) would be suitable to evaluate and to provide the basic resources for a Korean model of sleep/activity patterns during the new born baby, and to provide a basis for nursing intervention for mothers of new born baby. The subjects of this study were 38 normal new born baby who visited the postpartum care center and two general hospitals located in pusan from January 1 to April 28, 2000. They all agreed to participate in this study. The method of data collection was through convenient sampling. Data were collected through questionnaires including demographic data, birth hi story, and general informations concerning the infant, mother and family. The instrument of this study was the NCASA translated by the Korean parent Child Health Academic Association. The collected data were analysed by mean. standard deviation, frequency, and percentage by use of SPSS/PC. The conclusions obtained from this study are summarized as follows: 1. The mean amount of daytime sleep was 10.23 hours. The mean amount of nighttime sleep was 5.53 hours. The mean amount of total daily sleep was 15.77 hours. The mean of the longest sleep period was 4.49 hours. The mean regularity of daytime sleep was 49.69%. The mean regularity of nighttime sleep was 66.98%. The mean regularity of total daily sleep was 55.81%. The mean frequency of nighttime wakenings was 3.09 times. 2. The mean amount of daytime awake periods was 6.12 hours. The mean amount of nighttime awake periods was 2.11 hours. The mean amount of daily total awake periods was 8.23 hours. The mean of the longest awake periods was 3.76 hours. 3. The mean frequency of daytime feeding was 5.71 times. The mean frequency of nighttime feeding was 2.65 times. The mean frequency of total daily feeding was 8.36 times. The mean frequency regularity of feeding was 62.50%. 4. The mean amount of a mother's day time was 16.36 hours. The mean amount of a mother's night time was 7.64 hours. In conclusion, The new born baby slept more during the daytime compare than nighttime and more active during the daytime. On the other hand. although nighttime sleeping the length of the mother was normal, but sleep was interrupted by the infant over 3 times on average. Therefore this research study will contribute to nursing practice and nursing research by its implication through postnatal educational nursing programs at hospital and nursing intervention programs that would help individual caring of early infant mothers at home.