• Sleep Medicine and Psychophysiology
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• v.4 no.2
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• pp.147-155
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• 1997

To assess the reliability of chronobiological models of sleep/wake regulation, it is necerssary that the models predict the data which has been studied in sleep research, and they should be generalized across all ages. To date, many adult human data on such models have accumulated, yet it is evident that a comprehensive theory of the biorhythmic aspects of sleep/wake states has not established. Circadian rhythms such as the time going to bed, sleep onset, slow wave sleep pressure, periodicity of REM sleep, daytime performance, and early evening alertness are resumed everyday. Even in adult humans, sleep is inherently polyphasic. In both the disentrained and entrained states, naps when allowed tend to recur in a temporally lawful manner. The monophasic sleep pattern of most industrial societies therefore appears to be purely of social origin. The endogenous biorhythmic nature of circasemidian sleep tendency is supported by the ubiquity of the phenomenon across all ages. The NREM/REM sleep cycle within sleep with its inherent physiological, endocrine, and neurochemical fluctuations represents the best-documented ultradian sleep rhythms. Also, a daytime ultradian variation in sleepiness with a periodicity similar to nocturnal NREM/REM cycle(BRAC hypothesis) is suggested. This review article provides a brief synoptic review of the evidences for circadian, circasemidian, and ultradian sleep/wake rhythms, and then the authour will suggest the issues which expedite fuller modeling of sleep/wake system, to be further discussed.

• Sleep Medicine and Psychophysiology
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• v.5 no.1
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• pp.12-17
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• 1998

Circadian rhythms in subjective alertness, mood, and performance can be classified as psychological rhythm, compared with physiological rhythm such as body temperature and hormonal change. While in normal condition entrained by 24hr zeitgeber, subjective alertness would reach its maximum value around midday, subjective alertness would parallel body temperature rhythm with its peak at evening in non-entrained, free-running state. With desynchronization technique, subjective alertness rhythm is thought to be controlled by both temperature and sleep-wake rhythm oscillator. Circadian performance rhythms depend on the kind of task tested. It shows parallelism with body temperature rhythm when subjects are tested with simple, repetitive task. But when tested with tasks requiring complex verbal reasoning or immediate memory, subjects would perform them best at early morning, with performance decreasing as time of day advances. The desynchronization technique shows that circadian performance rhythm of simple, repetitive task is dependent on temperature oscillator but circadian performance rhythm of complex verbal reasoning is influenced by both temperature and sleep-wake rhythm oscillator or another independent oscillator. It would be worthwhile to compare psychological rhythm with hormonal change such as cortisol and melatonin. And more simple and time-saving method than desynchronization technique may facilitate the study of the mechanism underlying psychological rhythm.

• Sleep Medicine and Psychophysiology
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• v.23 no.1
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• pp.25-28
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• 2016

Objectives: The retinoid-related orphan receptor A (RORA) gene has been reported to have an impact on circadian rhythm regulation. In this study, we analyzed the relationship between the RORA gene polymorphism and diurnal preference in Korean young adults. Methods: A population of 504 young adults was included in the study. All subjects were given and completed a 13-item composite scale for morningness (CSM). The RORA gene rs11071547 single-nucleotide polymorphism (SNP) was genotyped by PCR-based methods. Results: CSM score was not associated with genotype or allele carrier status of the RORA rs11071547 SNP. Conclusion: This result indicates that the RORA rs11071547 SNP does not play a role in diurnal preference.

• Sleep Medicine and Psychophysiology
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• v.4 no.1
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• pp.57-65
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• 1997

As jet lag of modern travel continues to spread, there has been an exponential growth in popular explanations of jet lag and recommendations for curing it. Some of this attention are misdirected, and many of those suggested solutions are misinformed. The author reviewed the basic science of jet lag and its practical outcome. The jet lag symptoms stemed from several factors, including high-altitude flying, lag effect, and sleep loss before departure and on the aircraft, especially during night flight. Jet lag has three major components; including external de synchronization, internal desynchronization, and sleep loss. Although external de synchronization is the major culprit, it is not at all uncommon for travelers to experience difficulty falling asleep or remaining asleep because of gastrointestinal distress, uncooperative bladders, or nagging headaches. Such unwanted intrusions most likely to reflect the general influence of internal desynchronization. From the free-running subjects, the data has revealed that sleep tendency, sleepiness, the spontaneous duration of sleep, and REM sleep propensity, each varied markedly with the endogenous circadian phase of the temperature cycle, despite the facts that the average period of the sleep-wake cycle is different from that of the temperature cycle under these conditions. However, whereas the first ocurrence of slow wave sleep is usually associated with a fall in temperature, the amount of SWS is determined primarily by the length of prior wakefulness and not by circadian phase. Another factor to be considered for flight in either direction is the amount of prior sleep loss or time awake. An increase in sleep loss or time awake would be expected to reduce initial sleep latency and enhance the amount of SWS. By combining what we now know about the circadian characteristics of sleep and homeostatic process, many of the diverse findings about sleep after transmeridian flight can be explained. The severity of jet lag is directly related to two major variables that determine the reaction of the circadian system to any transmeridian flight, eg., the direction of flight, and the number of time zones crossed. Remaining factor is individual differences in resynchmization. After a long flight, the circadian timing system and homeostatic process can combine with each other to produce a considerable reduction in well-being. The author suggested that by being exposed to local zeit-gebers and by being awake sufficient to get sleep until the night, sleep improves rapidly with resynchronization following time zone change.

• Journal of Korean Biological Nursing Science
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• v.3 no.1
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• pp.1-10
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• 2001

뇌손상이라고 하는 과도한 stress를 받았을 때 free cortisol의 분비되는 양과 urinary free cortisol의 circadian 리듬에 어떻게 영향을 주는지 확인하기 위하여 시도하였다. 연구대상은 대조군은 건강한 젊은 여성 6명과 실험군응 CT상 뇌에 손상을 받은 4명의 여성으로 30대 환자이었다. 담당의사와 중환자실 관리책임자의 동의하에서 시도되었으며, 실험기간은 2000년 7월 1일에서 7월 10일까지였다. 대조군과 실험군의 뇨를 채취하여 뇨중 free cortisol 농도의 circadian rhythm을 알아보기 위해 채뇨 후 분석하였다. 채뇨는 뇌손상을 받고 응급실을 통해 신경외과 중환자실에 입원한 지 5시간 이내에 해당된 환자로 24시간 유지되는 foley catherization 상태하에서 12:00부터 3일동안 72시간을 2시간 간격으로 채뇨하였고, 대조군은 오전 12시부터 24시간 동안 2시간 간격으로 채뇨하였다. 측정방법으로는 cortisol의 정량은 solid-phase radioimmuoassay 방법을 이용하였으며, 분석재료는 Coat-A-Count(R) Cortisol kit(DPC, U.S.A.)을 사용하여 DPC사의 측정방법을 따랐다. 연구대상자의 free cortisol의 총량은 대조군에서는 $42.8{\mu}g$이었고, 실험군은 1일에 $991.2{\mu}g$, 2일에 $809{\mu}g$, 3일에 $544.2{\mu}g$으로 대조군과 통계적으로 유의한 차이를 나타내(p<.05), 실험군에서 현저하게 증가된 양상을 보였고, 시간이 지나면서 점점 감소하는 경향을 나타냈다. 시간별로 t-검정으로 분석한 결과로는 모든 시간대에서 대조군과 실험군의 평균치는 통계적으로 유의한 차이를 나타냈다. Free cortisol의 circadian에서는 대조군에서는 정상인의 cortisol의 circadian의 경우와 같은 리듬을 보였으나, 손상을 받은 실험군의 경우 분비량은 현저하게 증가했음을 보여주었다. 최고치가 제1일에 18:00과 다음날 10:00에 나타나 최고치가 2회 나타났으며, 제2일에도 제1일과 마찬가지로 18:00에 나타났고, 제3일에는 24:00에 나타나 제1일보다 제2일에는 최고치가 한 번 나타난 리듬을 보여주었고, 분비량은 2일에 감소하였다. 제3일에는 최고치가 8시간 지연된 나타난 리듬의 변화를 보여주었다. 최저치는 제1일, 제2일, 제3일 모두 24:00에 나타난 리듬을 보여주었다. 이상의 결과에서 실험군인 뇌손상 환자군에서는 뇌손상이 과도한 stress로 작용하여 환자의 free cortisol 분비량과 circadian 리듬에도 영향을 주는 것으로 나타났다. 그러므로 뇌손상환자를 간호하는 간호사는 스트레스상태인 것을 인지하여 환자 개개인에 필요한 간호를 해야 할 것으로 사료된다.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.5
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• pp.556-563
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• 1997

The endogenous gibberellin(GA) levels of sorghum grown under different photoperiodic conditions were measured by GC-MS-SIM. The effect of photoperiods on the diurnal GA levels of the 13-hydroxylation pathway was investigated by sampling every 6 h for 1 day. Levels of $GA_12$, $GA_53$, $GA_19$, $GA_20$, $GA_1$ and $GA_8$ were not constant throughout sampling times but rather rhythmic in productions. Wild-type seedlings grown under short photoperiod contained more $GA_20$ and $GA_1$ than those of long photoperiod. Although plant height of phyB-l(phytochrome B mutant) was taller than wild-type under all photoperiods tested, $GA_1$ concentration of wild-type grown under 10 h photoperiod was higher than that of phyB-l grown under the same photoperiod. These results are compatible with the idea that phytochrome B changed seedling responsiveness to GAs.

• Sleep Medicine and Psychophysiology
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• v.8 no.2
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• pp.129-137
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• 2001

Objectives: The purpose of this study is to investigate the effects of 38-hour sleep deprivation on fine motor performance. The Motor Performance Series (MPS) in the Vienna Test System (computerized neurocognitive function tests) was used in this study. Methods: Twenty four subjects participated in this study. Subjects had no past history of psychiatric disorders and physical illness. Subjects had normal sleep-waking cycle without current sleep disturbances and were all right-handed (Annett's Hand Preference Questionnaire: above +9 points). To minimize the learning effects, familiarization with the Vienna Test System was performed one day before the study. Subjects were to get up at 6:00 in the morning after getting enough sleep according to his or her usual sleep-wake cycle. After awakening, subjects remained awake for 38 hours under continuous surveillance. During two consecutive study days, the subjects tested MPS at 7 AM and 7 PM each day, which means the MPS was done four times in total. During the experiment, anything that could affect the subjects' sleep such as coffee, tea, alcohol, a nap, tiring sports, and all medications were prohibited. Results: In MPS, the fine motor functions of both hands decreased after 38 hours of sleep deprivation. The decrement in motor performance was prominent in the dominant right hand. In the right hand, the total number of tapping was reduced (p<.005), and the number of misses (p<.05) and the length of misses (p<.05) of line tracking, the total length of inserting a short pin (p<.01), the total length of inserting a long pin (p<.05), and the number of misses in aiming (p<.05) increased. Such performance decrement was distinct in the morning sessions. Conclusions: These results suggest that fine motor performance decrement during sleep deprivation is predominant in the right hand, which exerts maximal motor function. The finding of decrement in motor function in tapping during sleep deprivation also suggested that the time required for exhaustion of muscles is shortened during sleep deprivation. More deterioration of motor performance was shown in the morning, which could be explained as circadian rhythm effects.