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

• Korean Journal of Clinical Pharmacy
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• v.11 no.2
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• pp.57-61
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• 2001

The effect of circadian rhythm on the pharmacokinetics of acebutolol was studied in rabbits administered intravenous 5 mg/kg dose of acebutolol at 09:00 in the morning (a.m) and 22:00 in the evening (p.m). A significant effect of circadian rhythm of pbarmacokinetic parameters as a function of time of day was noted in rabbits, showing lower total body clearance (CLt), higher plasma concentration and the area under the plasma concentration time curve (AUC) when acebutolol was given in the evening. The plasma concentration of acebutolol was increased significantly (p<0.05) at 12-24 hr after dosing in the evening. The AUC was greater in the evening $(111\%)$ than that in the morning and $CL_t$, was higher when acebutolol was given in the morning ($1.12\pm0.24$ ml/hr) versus in the evening ($1.01\pm0.22$ ml/hr), but those were not significant. Therefore, It is reasonable to consider individual circadian rhythm for effective dosage regimen of acebutolol in clinical chronotherapeutics.

• International Journal of Advanced Culture Technology
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• v.6 no.2
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• pp.16-22
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• 2018

This study is a descriptive survey research to investigate the effect of the circadian rhythm of the college students in different departments on the addiction to SNS. The subjects of this study were 150 freshman students in the Department of Nursing in K university, a four-year university located in Gumi, Gyeongbuk, and 130 freshmen students in the Department of Mechanical Engineering in K Engineering university located in the same city. In this study, the difference of circadian rhythm and SNS addiction was analyzed among the subjects in different departments. The result showed that the circadian rhythm was not significantly different between the departments, but SNS addiction showed significant difference between the departments.

• The Journal of Korea CHUNA Manual Medicine
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• v.2 no.1
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• pp.169-175
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• 2001

Objects : The purpose of this study is find out significant (clinical) effect of applying acupuncture on $zh{\grave{a}}h{\grave{a}}i$(K6, 照海) of ${\bar{U}m-kyo-maek$(陰?脈) and $sh{\bar{e}}nm{\grave{a}}i$(B62, 申?) of Yang-kyo-maek(陽?脈) to a patient of circadian sleep disorder. Methods : We apply acupuncture on $zh{\grave{a}}h{\grave{a}}i$(K6, 照海) and $sh{\bar{e}}nm{\grave{a}}i$(B62, 申?) to a patient of circadian sleep disorder during 2 weeks. We check sleeping time day and night during 14 days. Acupuncture on $zh{\grave{a}}h{\grave{a}}i$(K6, 照海) and $sh{\bar{e}}nm{\grave{a}}i$(B62, 申?) has significant effect to circadian sleep disorder patient. Results : Acupuncture on $zh{\grave{a}}h{\grave{a}}i$(K6, 照海) and $sh{\bar{e}}nm{\grave{a}}i$(B62, 申?) has significant effect to circadian sleep disorder patient. Conclusions : 1. The physio-pathologic phenomenon of sleeping is relative to ${\bar{U}m-kyo-maek$(陰?脈) and Yang-kyo-maek(陽?脈) 2. Acupuncture therapy on $zh{\grave{a}}h{\grave{a}}i$(K6, 照海) and $sh{\bar{e}}nm{\grave{a}}i$(B62, 申?) has significant effect to circadian sleep disorder.

• Animal cells and systems
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• v.16 no.1
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• pp.27-33
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• 2012

The suprachiasmatic nucleus (SCN) of the teleost hypothalamus contains a central circadian pacemaker, which adjusts circadian rhythms within the body to environmental light-dark cycles. It has been shown that exposure to darkness during the day causes phase shifts in circadian rhythms. In this study, we examined the effect of exposure to darkness on the mRNA expression levels of two circadian clock genes, namely, $Period2$ ($Per2$) and $Cryptochrome1$ ($Cry1$), and the rate-limiting enzyme in melatonin synthesis, arylalkylamine $N$-acetyltransferase-2 (Aanat2), in the pineal gland of olive flounder, $Paralichthys$ $olivaceus$. The expression of these genes showed circadian variations and was significantly higher during the dark phase. These changes may be involved in the mechanism of dark-induced phase shifts. Furthermore, this study suggests that olive flounder may be a teleost model to investigate the localization and function of circadian oscillators.

• Korean Journal of Clinical Pharmacy
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• v.10 no.3
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• pp.125-129
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• 2000

The effect of circadian rhythm on gentamicin pharmacokinetics was studied in rabbits who took a single intravenous 2 mg/kg dose of gentamicin at 09:00 in the morning (a.m.) and 22:00 in the evening (p.m.). A significant circadian rhythm of pharmacokinetic parameters as a function of time of day was noted in rabbits, showing lower total body clearance $CL_t$ and higher serum area under the curve (AUC) when given in the evening. The half-life $t_{1/2}$ was shorter in the morning $(3.88\pm0.62h)$ when compared to the evening $(4.76\pm0.75\;h)$. The AUC was greater in the evening $(25.92\pm3.49\;{\mu}g/ml{\cdot}hr)$ than that in the morning $(22.42\pm3.42\;{\mu}g/ml{\cdot}hr)$, most likely because the CLt was significantly higher when gentamicin was given in the morning $(0.18\pm0.28\;ml/hr)$ versus in the evening $(0.15\pm0.26\;ml/hr)$. The $t_{1/2}$ of gentamicin in the evening was increased significantly(p<0.05) compared to those of gentamicin in the morning. It is reasonable to consider individual circadian rhythm for effective dosage regimen of gentamicin in clinical chronotherapeutics.

• Environmental Analysis Health and Toxicology
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• v.10 no.3_4
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• pp.7-13
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• 1995

The most periodlengths($\tau$) of conidiation of Neurospora were shortened in the medium with Li$^+$, Rb$^+$, and Cs$^+$ under the blue or green light. The higher the concentration of the heavy metal elements are, the shorter the circadian lengths are. The largest differences between the maxima- and minima circadian lengths showed in the medium with LiCI, RbCl, and CsCI under the blue lights at 150 Lux, while the little differences of circadian lengths presented in 1 mM heavy metal elements at the 270Lux blue light. Li$^+$ under the blue light effected extremely much and in the order of Rb$^+$ and Cs$^+$ on the conidiation of Neurospora. Under the green lights at 270Lux, the smallest changes of the circadian lengths are resulted in the medium with heavy metal elements. The other way at the green light 150Lux, the conidiation is stimulated by lmM LiCI or RbCl for the average 0.71h and 0.29h longer than the periodlength of control 28.34h. The medium with Li$^+$ under the green light has less effect on the conidiation rhythm of Neurospora than with Rb$^+$ or Cs$^+$.

• Journal of Korean Biological Nursing Science
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• v.1 no.1
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• pp.86-99
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• 1999

The purpose of this study is to find out the difference in circadian rhythm and level of fatigue between ER and General Ward Nurse. This study was done through analyzing body temperature, heart rate and major electrolytes such as $Na^+$ and $K^+$ concentration on urinalysis, which are related to factors of circadian rhythm and level of fatigue. The subjects, 17 nurses from Emergency Room and 25 nurses from general ward, were selected from a General Hospital in Taegu City on August 8 to 23, 1998. And the data were analyzed by proportion, t-test, chi-square and Pearson's Correlation, ANCOVA, using SAS program. The results of this study were shown as follows: First, The difference of Maximal and minimal heart rate was significant between ER group and general ward group. However, body temperature difference wasn't notable. Second, Urine $Na^+$ concentration on urinalysis was lower and $K^+$ concentration on urinalysis was higher in ER group than general ward group significantly. Third, Fatigue level was higher in ER group than general ward group significantly. Fourth, through urine concentration, significant relations in circadian rhythm of ER nurse group and general ward group and their fatigue level were found. Urine $Na^+$ concentration on urinalysis of ER nurse was significant related with their fatigue level. In conclusion, the effect of fatigue on circadian rhythm is greater in ER group than general ward group during night shift. This study could be a help in improvement of nurse's health and understanding the effect of fatigue on health.

• Journal of the Korean Wood Science and Technology
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• v.50 no.5
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• pp.338-352
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• 2022

Herein, water and ethanol extracts were obtained from the leaves, branches, kernels, and pericarp of Quercus gilva and subsequently analyzed for antioxidant activity and circadian rhythm regulation effects. Candidate components that may affect circadian rhythm and antioxidant activity were investigated to discover potential functional materials. Antioxidant activity was analyzed via 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity assays, showing that the hot water extract exhibited higher activity than that of the ethanol extract. In particular, the branch extract showed high antioxidant activity. By measuring total contents of polyphenols, flavonoids, and tannins, the hot water branch extract showed the highest concentrations, highlighting their significant contribution to the antioxidant activity. Examination of the circadian rhythm regulation of each extract showed that the ethanol extract exhibited greater impacts on the circadian rhythm amplitude compared to the water extract. The branch ethanol extract induced circadian rhythm amplitude changes via clock gene Bmal1 expression regulation. Determination of 12 phenolic compound concentrations showed that the branch ethanol extract contained many phenolic compounds, including catechin. This suggests that these com- pounds affected circadian rhythm regulation. In conclusion, the hot water branch extract has potential as an natural antioxidant material, while the corresponding ethanol extract has potential as a functional material for regulating circadian rhythm.

• Environmental Analysis Health and Toxicology
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• v.8 no.1_2
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• pp.11-17
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• 1993

Radioactive elements Li/sup +/, Rb/sup +/and Cs/sup +/ effect the period shortening in proportion to the higher concentration on the growth of Neurospora crassa. 1 mM LiCl presented the result of the period length 0.52 h shorter than average circadian rhythm 21.66 h. 1 mM RbCl reduced the period length 1.13 h than control period 21.89 h and 1 mM CsCl reduced 2.12 h than control period 21.89 h. In the equal concentration Cs/sup +/ had an extreme effect. Fatal doses of Li/sup +/, Rb/sup +/ and Cs/sup +/ are 20mM, 30mM and 20mM. In the fatal concentration Neurospora didn't develop more after 7 days and the formation of spores were not given in regular order. Circadian length of Neurospora decreased generally at the last cycle of the growth.