• Korean Journal of Occupational Health Nursing
• /
• v.9 no.2
• /
• pp.86-93
• /
• 2000

This study was conducted to find out the degree of tiredness, accumulated tendencies of fatigues in accordance with 3 types of circadian rhythms and 3 types of perceived fatigue signs such as physical, psychological and neurosensory aspects in before and after work at night. Samples were chosen from the 217 intensive care units nurses working in 13 general hospitals which had 3 shift rotating systems, Data were collected from November to December in 1999. Two hundreds seventeen respondents were classified by 3 circadian types such as 59 morning, 110 middle and 48 evening. Circadian type was measured by the circadian type scale which was designed by ${\ddot{O}}stberg$ and Home (1976). in order to estimate the level of tiredness, the investigator used the fatigue checklist designed by the Labor and Health Institute of Japan(1970). Analysis was done by frequency a percentages, ${\chi}^2$ test and repeated measures ANOVA test. The result of this study were as follow: 1. In the general characteristics of the subjects circadian types, moderate type had the large proportion at 50.7% and morning type had 27.2% and evening type had 22.1%. 2. According to the 3 types of fatigue signs, the highest general tendency was 'General weakness' and 'Feeling of headsore' for physically perceived sign, 'Drowsiness' for psychological sign, and 'Uncomfortableness in sight seeing' for neurosensory sign. 3. The most frequently complained fatigue were observed in physical symptoms among physical, mental, and neurosensual symptoms. The percentage of complained was higher after night work than before the work started. 4. There was not any statistical significant difference between the circadian type and the degree of physical, mental, neurosensory fatigue. 5. There was not any statistical significant difference in regarding to each date of night shift except difference between 1st and 2nd days of fatigue perceived physically. Therefore, the study concluded that the fatigue perceived by night shift nurses might be related with shift working condition rather than circadian types.

• Journal of Korean Biological Nursing Science
• /
• v.19 no.3
• /
• pp.198-205
• /
• 2017

Purpose: The purpose of this study was to identify sleep patterns, alertness, and fatigue of shift nurses according to circadian types. Methods: The researchers' enrolled 17 nurses doing shift work in a tertiary hospital. To evaluate circadian types, a morningness-eveningness questionnaire (MEQ) was administered. Sleep patterns were examined using an actigraph for 14 days. To assess alertness and fatigue, Visual Analogue Scale (VAS) was used. The data were analyzed using ANOVA and Kruskal-Wallis test with a SPSS 21.0 program. Results: The researchers found that 17.6% of participants reported morning type, 47.1% neither type, and 35.3% evening type. Mean total sleep time (TST) was 6.8 h, mean sleep efficacy was 82%, level of alertness was 6.54, and level of fatigue was 5.49, regardless of the type of shift work. Evening type nurses had higher variation in TST and alertness, according to the shift patterns than other circadian type nurses. Evening type nurses also had higher fatigue levels than other circadian type nurses. Conclusion: Sleep, alertness, and fatigue were related with circadian types. These results suggest that circadian rhythm management in shift work nurses, particularly in evening type nurses is urgently needed to improve sleep patterns, alertness, and to decrease the level of fatigue.

• Korean Journal of Biological Psychiatry
• /
• v.23 no.4
• /
• pp.173-178
• /
• 2016

Objectives The purpose of this study was to investigate the relationships among circadian types, depressive mood and internet addiction and to identify the mediating effect of depressive mood between circadian types and internet addiction in Korean College Students. Methods A total of 2632 participants completed questionnaires, which included the Korean translation of the Composite Scale of Morningness (CSM), the Patient Health Questionnaire (PHQ-9), and the Korean version of the Internet Addiction Test (KIAT). Statistical analyses were done using correlation analysis, analysis of covariance and multiple linear regression. Results The CSM score was negatively associated with the PHQ-9 score (r = -0.226, p < 0.001) and the KIAT score (r = -0.218, p < 0.001). The eveningness group showed higher scores in depressive mood and internet addiction than the morningness group (p < 0.001). Depressive mood showed a partial mediating effect between circadian types and internet addiction (${\beta}=0.255$, p < 0.001). Conclusions Internet addiction was associated with circadian types and depressive mood. These results suggest that depression and circadian rhythm management would contribute to the prevention of internet addiction.

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

• Korean Journal of Biological Psychiatry
• /
• v.21 no.3
• /
• pp.93-98
• /
• 2014

Objectives Circadian rhythms have been known to have associations with psychiatric disorders and personality traits. The present study investigated the relationships between circadian typology and temperaments/characters in a non-clinical Korean population. Methods Two hundred six healthy Korean college students (male 109, female 97) participated in this study. The subjects completed the Composite Scale of Morningness for circadian typology and 140-item Temperament and Character Inventory-Revised-Short version (TCI-RS). Results Multivariate analyses of covariance showed a significant association between chronotypes and temperamental dimensions of the TCI-RS. Morning types were significantly associated with lower harm avoidance and higher persistence and self-directedness dimensions, compared to evening types and intermediate types. No interaction effects between sex and chronotypes were shown for temperamental dimensions. Conclusions The present findings suggest that high persistence and self-directedness characters are related to morning types and high harm avoidance temperament is more related to evening types.

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

• Journal of Life Science
• /
• v.27 no.10
• /
• pp.1225-1231
• /
• 2017

Disruptive expression patterns of the circadian clock genes are highly associated with many human diseases, including cancer. Cell cycle and proliferation is linked to a circadian rhythm; therefore, abnormal clock gene expression could result in tumorigenesis and malignant development. The molecular network of the circadian clock is based on transcriptional and translational feedback loops orchestrated by a variety of clock activators and clock repressors. The expression of 10~15% of the genome is controlled by the overall balance of circadian oscillation. Among the many clock genes, Period 1 (Per1) and Period 2 (Per2) are clock repressor genes that play an important role in the regulation of normal physiological rhythms. It has been reported that PER1 and PER2 are involved in the expression of cell cycle regulators including cyclins, cyclin-dependent kinases (CDKs), and CDK inhibitors. In addition, correlation of the down-regulation of PER1 and PER2 with development of many cancer types has been revealed. In this review, we focused on the molecular function of PER1 and PER2 in the circadian clock network and the transcriptional and translational targets of PER1 and PER2 involved in cell cycle and tumorigenesis. Moreover, we provide information suggesting that PER1 and PER2 could be promising therapeutic targets for cancer therapies and serve as potential prognostic markers for certain types of human cancers.

• Proceedings of the ESK Conference
• /
• 1996.10a
• /
• pp.103-107
• /
• 1996

The menstrual cycle is repeated as long as a female is capable of bearing young, except during pregnancy and also for a certain length of time after the period of pregnancy. In this study, menstrual cycle and circadian rhythm of body temperature in young women are presented. Also, the specifications of different types in menstrual cycle and circadian rhythm are discussed to define the physiolosical temperature regulatuion system.

• BMB Reports
• /
• v.48 no.12
• /
• pp.677-684
• /
• 2015

Cardiovascular function is regulated by the rhythmicity of circadian, infradian and ultradian clocks. Specific time scales of different cell types drive their functions: circadian gene regulation at hours scale, activation-inactivation cycles of ion channels at millisecond scales, the heart's beating rate at hundreds of millisecond scales, and low frequency autonomic signaling at cycles of tens of seconds. Heart rate and rhythm are modulated by a hierarchical clock system: autonomic signaling from the brain releases neurotransmitters from the vagus and sympathetic nerves to the heart's pacemaker cells and activate receptors on the cell. These receptors activating ultradian clock functions embedded within pacemaker cells include sarcoplasmic reticulum rhythmic spontaneous Ca²⁺ cycling, rhythmic ion channel current activation and inactivation, and rhythmic oscillatory mitochondria ATP production. Here we summarize the evidence that intrinsic pacemaker cell mechanisms are the end effector of the hierarchical brain-heart circadian clock system.

• Journal of Korean Clinical Nursing Research
• /
• v.19 no.3
• /
• pp.309-320
• /
• 2013

Purpose: This study was conducted to identify relationships among circadian types, sleep quality, and adaptation to night shifts among nurses working on two or three day night duties. Methods: The participants were 199 ward nurses from two university hospitals in Gyeongnam province. Each nurse worked on two or three day night duties. Data were collected between September 24 and October 14, 2012 and analyzed using t-test, ANOVA, $Scheff{\grave{e}}$ test, Pearson correlation, and multiple regression with SPSS/WIN 14.0 program. Results: Mean scores for sleep quality and adaptation to night shifts was $4.92{\pm}1.46$ on a 10-point scale and $2.66{\pm}0.47$ on a 5-point scale respectively. There were no significant differences in sleep quality and adaptation to night shifts according to circadian types of nurses. There were significant correlation between sleep quality and adaptation to night shifts (r=.25, p<.001). Factors affecting adaptation to night shifts were preference for night shifts, and subjective health status, which together explained about 35% of the total variance. Conclusions: Nurses working on two or three day night duties had low level of sleep quality and adaptation to night shifts. It is necessary to improve preference for night shifts and subjective health status for improving adaptation to night shifts of nurse.