• Sleep Medicine and Psychophysiology
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• v.10 no.2
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• pp.108-112
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• 2003

Objectives: The purpose of this study is to investigate the psychophysiological effects of total sleep deprivation by using auditory event-related potentials. Methods: Twenty four healthy college students (18 men, 6 women) participated in this study. The subjects remained awake for 37 hours under continuous surveillance. In the morning and the evening of two consecutive study days, auditory event-related potentials were checked. Results: The latencies of P300 and N200 were significantly prolonged (p<0.001) and their amplitudes decreased (p<0.05) as a consequence of sleep deprivation. The amplitude of P200 was significantly increased during sleep deprivation (p<0.05). However, there was no significant change in the latency and amplitude of N100. Conclusion: Among the components of auditory event-related potentials, P300 and N200 are good indicators of sleep-deprived status. Further investigation is necessary to elucidate the neurophysiological mechanisms of these findings.

• Korean Journal of Culture and Social Issue
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• v.12 no.3
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• pp.69-83
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• 2006

The purpose of the present driving simulation study was to investigate the effects of fatigue induced both by sleep deprivation and time-on-task on driver's driving performance. The results are as followings. First, although the drivers in almost every experimental conditions showed faster driving speed than that was required, the drivers in the sleep-deprivation and over 1-hour time-on-task condition drove slower than the target speed. Second, the drivers in the sleep-deprivation and over 1-hour time-on-task condition crossed the lane less frequently than those in the other conditions, they weaved more in the lane. Third, as the drivers became more fatigued both by sleep deprivation and continuous driving, they reported higher fatigue scores in the subjective fatigue ratings. The results suggested that although the drivers might adapt a compensative driving strategies when they were fatigued, their driving performances were indeed impaired, in general.

• Sleep Medicine and Psychophysiology
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• v.9 no.2
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• pp.122-126
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• 2002

Objectives: The purpose of this study is to investigate the effects of the 37-hour sleep deprivation on visual discrimination using the Cybernetic Flicker Fusion Analyzer (FLIMK) and to see the correlation between this finding and various subjective scale scores. Methods: Twenty six subjects (20 men 6 women, $24.50{\pm}1.45$ years of age) participated in this study. Subjects remained awake for 37 hours under continuous surveillance. In the morning and evening of two study days, the FLIMK and the self-reporting scale of sleepiness, fatigue, anxiety and mood states were instituted. Results: In FLIMK, the flicker fusion threshold was significantly decreased after sleep deprivation (F=7.66, p=0.01). The number of trials (responses) before reaching fusion frequency threshold was significantly increased after sleep deprivation (F=13.16, p=0.001). The reduction of fusion frequency was correlated with the increase of sleepiness and fatigue (p<0.05), and the number of the trials was correlated with the scores of negative mood, anxiety, and fatigue (p<0.05). Conclusions: These results suggest that 37 hour total sleep deprivation cause the decrement in visual discrimination. The decrease of the fusion frequency after sleep deprivation was correlated with sleepiness and fatigue. Further study is needed to enlighten the biological mechanism of the decrement in visual function after sleep deprivation.

• Sleep Medicine and Psychophysiology
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• v.7 no.2
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• pp.88-95
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• 2000

Objectives: The object of this experiment was to evaluate the effect of sleep deprivation on mood states of normal adults using a subjective scale and an objective scale, minimizing the effect of other factors other than that of sleep deprivation. Methods: Seventy volunteers were first participated in this sleep deprivation schedule, and 36 of them completed this experiment. The subjects and the control group members were all in their early 20's (mean $age=20.8{\pm}1.35$ vs $20.6{\pm}1.10$) and in good health. A log was checked by these subjects from a week before the laboratory study started. Drugs, alcohol and beverages containing any caffeine had been prohibited for a week before and during sleep deprivation periods. The study was performed only in summer to control other factors like sunlight, temperature and moisture. Before this experiment, the subjects had slept adequately for a week at least. On day 1 of the experiment the subjects got up at 6 a.m. and stayed in a sleep laboratory without sunlight or external noises. They could only go about their daily routines. They were forbidden to have a nap and be drowsy. GVA (Global Vigor and Affect) and MADRS (Montgomery-Asberg Depression Rating Scale) were checked 11 times. The data was analysed focusing on the changing mood states. Results: The mood during sleep deprivation became worse as the sleep deprivation time progressed. Especially 20 hours ($GA=59.25{\pm}8.06$, $MADRS=3.43{\pm}1.25$) and 40 hours ($GA=38.83{\pm}9.22$, $MADRS=6.08{\pm}1.46$) after sleep deprivation, there were significant changes compared to the control group ($MADRS=6.08{\pm}1.46$ vs $1.07{\pm}1.18$, p<0.001). Conclusions: While controlling factors other than sleep deprivation might have had some influence on mood changes, significant mood changes during sleep deprivation were observed. The mood states became worse as the sleep deprivation progressed.

• Sleep Medicine and Psychophysiology
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• v.6 no.1
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• pp.76-84
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• 1999

Objectives: A number of studies have shown that sleep deprivation results in reduced vigilance and increased negative affects such as tension, depression and anger. However there are few studies about effects of sleep deprivation on anxiety. The purpose of this study was to investigate the effects of 40 hour sleep deprivation on state anxiety, affects, sleepiness and fatigue. The authors also intended to study the effect of trait-anxiety on these psychological variables after sleep deprivation. Methods: Twenty nine subjects(22 men, 7 women, $24.59{\pm}1.35$ years of age) participated in this study. Subjects had no past history of psychiatric disorders and physical illnesses, and had normal sleep-waking cycle without current sleep disturbances. All of the subjects completed sleep dairy for two weeks to exclude some who suffered from chronic sleep deprivation or sleep disturbances. Subjects were instructed to get a normal sleep as usual at night before the study. After awakening, subjects remained awake for 40 hours under continuous surveillance. They completed State-Trait Anxiety Inventory, Index of General Affect, Stanford Sleepiness Scale and Fatigue Questionnaire every three hours, therefore they completed the scales 14 times totally. Subjects were dictated not to take caffeine, alcohol, or any medications on the day of the study. Heavy exercises and naps were restricted too. Results: Sleep deprivation resulted in increased state anxiety, negative general affects, and increased sleepiness and fatigue(p<.001). Dividing into high trait-anxiety group and low trait-anxiety group, there was significant sleep deprivation x traitanxiety interaction effect on general affect(p<.05). But, there was no significant sleep deprivation x trait-anxiety interaction effect on state-anxiety, sleepiness and fatigue. During sleep deprivation, the highest ratings of scales on anxiety, negative affect, sleepiness and fatigue occurred between 4 : 00AM and 7 : 00AM. Conclusions: These results show that sleep deprivation results in increased anxiety, mood state disturbance and increment of sleepiness and fatigue. These findings also suggest that trait-anxiety is a factor that influences the degree of worsening in general affect caused by sleep deprivation. During sleep deprivation, the rating curves of anxiety, affect, sleepiness and fatigue show rhythmicity that may be related to circadian rhythm.

• Proceedings of the Safety Management and Science Conference
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• 2013.11a
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• pp.561-567
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• 2013

본 연구는 졸음운전의 지표로 예상되는 심전도의 LF/HF 비율이 효과적으로 졸음운전을 예측하는지를 검증하는 것이었다. 본 연구는 총 31명이 참가하였으며, 가상 운전 시뮬레이션 과제를 활용하여 진행하였다. 수면박탈이 운전 중 LF/HF 비율에 영향을 미치는지를 검증하기 위해 충분한 수면을 취한 조건과 수면이 박탈된 조건으로 실험을 실시하였다. 충분한 수면을 취한 조건에서 참가자는 전날 6시간 이상의 수면을 취한 후 30분동안 진행되는 가상 운전과제를 수행하였다. 수면이 박탈된 조건에서는 실험에 참여하기 전날에 참가자가 5시간 이하의 수면을 취하도록 유도한 후 60분 동안 진행되는 가상 운전 과제에 참여하도록 하였다. 참가자는 두 조건 모두에서 심전도를 측정할 수 있는 장비를 착용한 상태로 가상 운전 과제를 수행하였다. LF/HF 비율과 지각된 졸음운전과의 관계성을 확인하기 위해서 참가자가 가상 운전 과제를 수행하는 동안 10분간격으로 주관적 졸림정도를 측정하였다. 실험 결과 충분한 수면을 취한 조건보다 수면박탈 조건에서 참가자의 LF/HF 비율이 감소하였으며, 동일하게 주관적 졸림정도는 증가하였다. 또한 주관적 졸림정도가 LF/HF비율을 예측하는 것으로 나타났다. 따라서 LF/HF 비율을 통한 졸음 운전 예측은 타당한 것으로 나타났다.

• Sleep Medicine and Psychophysiology
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• v.10 no.1
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• pp.61-66
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• 2003

Objectives: The purpose of this study is to investigate the relationship between the extent of prolongation in P300 latency by sleep deprivation and personality variables. Methods: Eighteen healthy male college students participated in this study. Subjects remained awake for 37 hours under continuous surveillance. In the morning and evening of two consecutive study days, P300 was checked four times. MMPI and STAI-T were checked in the morning of the first day. The 18 subjects were divided into two groups according to their extent of P300 prolongation by sleep deprivation: Group A consisted of short P300 latency prolonged subjects, and group B of long latency prolonged subjects. The MMPI profiles and STAI-T scores of these two groups were compared. Results: Group B showed significantly higher scores in the Mf subscale (t=-2.16, df=16, p=0.046) and Pa subscale (t=-2.61, df=16, p=0.019) than group A. Group B also showed higher F subscale scores at a marginally significant level (t=-2.11, df=16, p=0.052). Conclusion: These results suggest that subjects with higher scores in F, Mf, and Pa subscales tend to have delayed cognitive process and decreased efficiency of mental process by sleep deprivation. It can be hypothesized that individuals who are sensitive, passive, dependent, and easily projecting are susceptible to the deterioration of cognitive function by total sleep deprivation.

• Sleep Medicine and Psychophysiology
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• v.3 no.1
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• pp.15-24
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• 1996

After rapid eye movement(REM) sleep was idenified in 1953, a lively interest developed concerning a possible role of this kind of sleep in memory processes. The author reviewed studies relating REM to memory/learning. Many studies in animals and humans gave substantial evidence for relating REM sleep to memory function. The evidence supporting the position taken in this paper comes from experiments showing that : (1) learning session is followed by the significant augmentation of REM sleep : (2) REM sleep deprivation, prior to learning or immediately thereafter, impairs the formation of a permanent memory/learning : (3) there is a vulnerable period of time(eg, REM sleep "window") following succussful learning, during which REM sleep deprivation results in memory impairment : (4) theta rhythm which develops during REM sleep induces long-term potentiation in hippocampus : (5) there are some evidences providing the relationship of neurotransmitter systems to the maintenance of REM sleep and memory storage processes.

• 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.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.47 no.2
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• pp.43-49
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• 2010

Autonomic nervous system (ANS) acts as a control system functioning largely below the level of consciousness, and controls visceral functions. The activity of the ANS has been assessed by means of the heart rate variability (HRV). It has been reported that HRV is dependent on sex, age, body mass index, and smoking, etc. However, the effects of posture and sleep deprivation on HRV have rarely been reported. Objective of our work was to find out which posture is appropriate for stable HRV. We measured the number of sleep deprivation and HRV using power spectrum in six stages for 30 minutes. Increased low frequency (LF) power and high frequency (HF) power indicate enhanced sympathetic and parasympathetic activity, respectively. We determined the LF/HF ratio to minimize individual difference. It was found that sleep deprivation by awakening up subjects was affected by posture, which resulted in changes of LF/HF. Although LF/HF varied with time, it was more stable in sitting than in supine. In conclusion, we recommend sitting posture when measuring HRV because of less sleep deprivation resulting in less variation in LF/HF.