OBJECTIVES: To find evidence that sleep is necessary for normal brain function, thus indicating that declines in both sleep quality and quantity are related to worse performance of many daily tasks and deteriorated physical functions. The present study investigates the relationships of balance control and reaction time with sleep quality. METHODS: 58 healthy (male 20, female 38) volunteers with informed consent participated in this study. The Self-reported Pittsburgh Sleep Quality Index (PSQI) was used to evaluate sleep quality and relevant factors, and the subjects were divided into groups A (PSQI < 5) and B (PSQI ≥ 5) based on this index. Static balance control and reaction time to visual stimuli were conducted to assess their relationship with sleep quality. RESULTS: Group B exhibited excessive daytime sleepiness significantly more often compared to group A. Static balance control did not markedly change relative to sleep quality, but reaction time and error to visual stimuli were significantly increased in group B compared to group A. CONCLUSION: These findings indicate that a decline in sleep quality can result in delayed reactions, as well as decreased accuracy of these reactions. They also suggest that low sleep quality may be associated with changes in physical functions, including balance control through reduced selective attention.
Brain ; Female ; Humans ; Informed Consent ; Physical Phenomena ; Reaction Time* ; Volunteers

OBJECTIVES: We aimed to evaluate the effects of mattress type on both objective and subjective sleep quality in healthy good sleepers. METHODS: Fifteen healthy good sleepers with a mean age of 30.8 years participated in this study. A randomized crossover trial was carried out using two different mattress types: a standard mattress and a contour coil mattress. After a night of adaptation, all participants were randomized to either a standard mattress or a contour coil mattress. Then, nocturnal polysomnography was conducted for two consecutive nights. Subjective evaluations were obtained using a self-report questionnaire before and after the polysomnographic recording sessions. RESULTS: The polysomnographic showed no differences in total sleep time, sleep stage, or wake time after sleep onset between the two mattress conditions. Of the polysomnographic variables, only sleep onset latency was significantly reduced for the contour coil mattress. Additionally, participants reported better subjective sleep quality when sleeping on the contour coil mattress, according to the questionnaires. CONCLUSION: The type of mattress might affect not only subjective, but also objective sleep quality, including sleep onset latency.
Polysomnography ; Sleep Stages

OBJECTIVES: Exposure to light at night has become pervasive in modern society. The impact of dim artificial light at night (dALAN) exposure on sleep and fatigue is not well recognized. We aim to study the impact of dALAN exposure during sleep on human fatigue. METHODS: 30 healthy young male volunteers from 21 to 29 years old were enrolled in the study. They were randomly divided into two groups depending on light intensity (Group A : 5 lux and Group B : 10 lux). Data were gathered from each participant after each night with no light (Night 1) followed by the next night (Night 2) with two different dim light conditions (5 or 10 lux) by means of self-reported fatigue scale. RESULTS: Exposure to dALAN during sleep was significantly associated with increased overall fatigue (F = 19.556, p < 0.001) and ocular discomfort (F = 5.671, p = 0.028). CONCLUSION: We found that dALAN during sleep likely affects human fatigue in some aspects. These findings indicate that dALAN during sleep exerts a negative effect on human fatigue.
Fatigue* ; Humans* ; Male ; Volunteers

Changes in core body temperature are closely related to initiation and maintenance of sleep, and are influenced by various factors such as air temperature, room temperature, clothing, human activities, and medications. These factors are closely related to sleep fragments, insomnia and other sleep disorders. Understanding the effect of the temperature related to human surroundings on the core body temperature and sleep, will be useful for understanding the physiology of sleep and to treat sleep disorders.
Body Temperature ; Circadian Rhythm ; Clothing ; Human Activities ; Humans ; Physiology ; Sleep Disorders ; Sleep Initiation and Maintenance Disorders

INTRODUCTION: Sleep has numerous important physiological and cognitive functions that may be particularly important to elite athletes. Sleep deprivation can have significant effects on athletic performance. However, there are few published data related to the amount of sleep obtained by elite athletes. We investigated sleep patterns of Korean women golfers using sleep-related questionnaires. METHODS: For this study, 98 Korean university women golfers and 46 age- and sex-matched controls were recruited. All subjects were asked to complete the self-administered sleep questionnaire consisting of questions about habitual sleep patterns (sleep onset time, sleep latency, awakening time in the morning, day time napping time), exercise habits, Epworth Sleepiness Scale (ESS), Insomnia Severity Index (ISS), Pittsburgh Sleep Quality Index (PSQI), validation of the Perceived Stress Scale (PSS), and Beck Anxiety Inventory (BAI). RESULTS: The sleep onset time was significantly earlier (pm 23 : 05 +/- 00 : 52 and 00 : 14 +/- 00 : 51 ; t = 5.287, p < 0.001), the waking time was later (am 07 : 21 +/- 01 : 09 and 6 : 35 +/- 00 : 32; t = -2.715, p = 0.008), the weekday total sleep time was greater (417.77 +/- 78.18 minute and 351.52 +/- 77.83 minute ; t = 4.406, p = 0.001), and the daytime nap time was greater (77.73 +/- 41.28 minute and 20.22 +/- 33.03 minute ; t = 7.623, p < 0.001) in the golf athletes compared to the controls. The PSQI scores were significantly lower, but estimated sleep latency and ESS, ISS, PSS, and BAI scores were not different among the two groups. CONCLUSION: This study suggests that Korean university women golfers have good sleep patterns resulting in no difference in sleep-related stress compared to age- and sex-matched control students.
Anxiety ; Athletes ; Athletic Performance ; Female ; Golf ; Humans ; Surveys and Questionnaires ; Sleep Deprivation ; Sleep Initiation and Maintenance Disorders

OBJECTIVES: Shift work is a stressful situation. It is important to know the factors associated with the ability to adapt to a shift work schedule. The aim of the present study was to investigate the association between sleep, as well as personality variables, and the resilience of shift work nurses. METHOD: Self-report questionnaires were administered to 95 nurses who worked in one national university hospital. Connor-Davidson resilience scale, hospital anxiety and depression scale, morningness-eveningness scale, Pittsburgh sleep quality index, other sleep-related questionnaires, and Korean defense style questionnaires were used. RESULTS: Age, shift work duration, off-day oversleep, depression, anxiety, adaptive defense style, and self-suppressive defense style were significantly associated with resilience (p < 0.05). Multiple regression analysis showed that age (beta = 0.34, p < 0.05), depression (beta = -0.25, p < 0.05), adaptive defense style (beta = 0.45, p < 0.001), and self-suppressive defense style (beta = -0.19, p < 0.05) significantly predicted the resilience of shift work nurses. Concerning individual defense mechanisms, resignation (beta = -0.20, p < 0.05), sublimation (beta = 0.19, p < 0.05), omnipotence (beta = 0.19, p < 0.05), and humor (beta = 0.20, p < 0.05) significantly predicted the resiliency. CONCLUSION: The findings indicate that a specific defense style and other mechanisms were associated with the resilience of shift work nurses. A future prospective study with more participants could further clarify the relationship between sleep-related variables, as well as personality factors, and resilience of shift work nurses.
Anxiety ; Appointments and Schedules ; Defense Mechanisms ; Depression ; Surveys and Questionnaires ; Sublimation

OBJECTIVES: This study was designed to assess the change of heart rate variability (HRV) at resting, upright, and psychological stress in anxiety disorder patients. METHODS: HRV was measured at resting, upright, and psychological stress states in 60 anxiety disorder patients. We used visual analogue scale (VAS) score to assess tension and stress severity. Beck depression inventory (BDI) and state trait anxiety inventories I and II (STAI-I and II) were used to assess depression and anxiety severity. Differences between HRV indices were evaluated using paired t-tests. Gender difference analysis was accomplished with ANCOVA. RESULTS: SDNN (Standard deviation of normal RR intervals) and low frequency/high frequency (LF/HF) were significantly increased, while NN50, pNN50, and normalized HF (nHF) were significantly decreased in the upright position compared to resting state (p < 0.01). SDNN, root mean square of the differences of successive normal to normal intervals, and LF/HF were significantly increased, while nHF was significantly decreased in the psychological stress state compared to resting state (p < 0.01). SDNN, NN50, pNN50 were significantly lower in upright position compared to psychological stress and nVLF, nLF, nHF, and LF/HF showed no significant differences between them. CONCLUSION: The LF/HF ratio was significantly increased after both physical and psychological stress in anxiety disorder, but did not show a significant difference between these two stresses. Significant differences of SDNN, NN50, and pNN50 without any differences of nVLF, nLF, nHF, and LF/HF between two stresses might suggest that frequency domain analysis is more specific than time domain analysis.
Anxiety ; Anxiety Disorders* ; Autonomic Nervous System ; Depression ; Equipment and Supplies ; Heart Rate* ; Humans ; Stress, Psychological*

OBJECTIVE: The aim of the present study is to assess the prevalence and related risk factors of suicide ideation among middle and high school students in an urban area. METHODS: We surveyed 3,691 middle and high school students (2,159 male, 1,532 female, 11-19 years of age) using a self-report questionnaire that covered basic socio-demographic data, academic achievements, presence of physical or psychiatric illness, sleep duration on weekdays, time spent at private academies on weekdays and weekends, and subjective needs for counseling. The Beck Depression Inventory (BDI) and Reynolds' Suicidal Ideation Questionnaire (SIQ) were included in the survey. RESULTS: The prevalence of students with high suicide ideation (SIQ > or = 62) was 4.6%. In a logistic regression model, female sex (p = 0.002), younger age (p < 0.001), poor academic achievement (p = 0.043) and higher score of BDI (p < 0.001) were associated with a higher SIQ score. In addition, younger age (p = 0.045) and a higher BDI score (p < 0.001) were associated with a higher SIQ score adolescents having high suicide ideation (SIQ > or = 62). CONCLUSION: Related risk factors of suicide ideation in adolescents were female sex, younger age, poor academic achievement, and a depressive mood. It would be especially helpful to pay more attention to younger adolescents and a depressive mood as a high-risk group. The understanding of these factors will be helpful for providing an effective suicide screening and prevention program for adolescents.
Academies and Institutes ; Adolescent* ; Counseling ; Depression ; Female ; Humans ; Logistic Models ; Male ; Mass Screening ; Prevalence* ; Surveys and Questionnaires ; Risk Factors* ; Suicidal Ideation* ; Suicide

A 'circadian rhythm' is a self-sustained biological rhythm (cycle) that repeats itself approximately every 24 hours. Circadian rhythms are generated by an internal clock, or pacemaker, and persist even in the absence of environmental time cues, collectively termed 'zeitgebers.' Although organisms generate circadian rhythms internally, they are entrained by environmental stimuli, particularly the light-dark cycle. Measurement of the endogenous melatonin rhythm provides relatively reliable surrogate way of assessing the timing of the internal circadian clock. Also, core body temperature and cortisol can be used as markers of circadian rhythms. The sleep-wake cycle, body temperature, and melatonin rhythm have a stable internal phase relationship in humans and other diurnal species. They play an important role in controlling daily behavioral rhythms including task performance, blood pressure, and synthesis and secretion of several hormones. In this review, we address not only the properties, methods of measurement, and markers of circadian rhythms, but also the physiological and psychological importance of human circadian rhythms.
Blood Pressure ; Body Temperature ; Circadian Clocks ; Circadian Rhythm* ; Cues ; Humans ; Hydrocortisone ; Melatonin ; Photoperiod ; Task Performance and Analysis

Adenotonsillar hypertrophy is the leading cause of childhood obstructive sleep apnea. Obstructive sleep apnea syndrome in child-hood, however, can occur from various causes such as obesity or craniofacial abnormalities. Childhood obstructive sleep apnea syndrome can be accompanied by enuresis, parasomnias and behavior problems. For patients with the symptoms of snoring and apnea, obstructive sleep apnea should be suspected and diagnosed properly. In addition, the evaluation of complications and proper treatment are indispensable. When the cause of childhood obstructive sleep apnea is adenotonsillar hypertrophy, symptoms can be improved by surgical methods. If the cause is other than adenotonsillar hypertrophy, such as obesity, it should be treated with other therapeutic modalities, like nasal continuous positive airway pressure (nCPAP), weight reduction and modification of life style. This paper reports a case of nCPAP used to manage severe sleep apnea when it was not resolved after adenoidectomy and tonsillectomy. Differential diagnosis of narcolepsy in a case with excessive daytime sleepiness and reflections on accompanying enuresis and parasomnia were also described.
Adenoidectomy ; Apnea ; Child ; Continuous Positive Airway Pressure ; Craniofacial Abnormalities ; Diagnosis, Differential ; Enuresis ; Humans ; Hypertrophy ; Life Style ; Narcolepsy ; Obesity ; Parasomnias ; Sleep Apnea Syndromes ; Sleep Apnea, Obstructive* ; Snoring ; Tonsillectomy ; Weight Loss