In accordance with the development of EEG and polysomnography in the field of sleep research, the sleep onset period (SOP) between wakefulness and sleep has been considered an important part for understanding the physiology of sleep. SOP in the transition from wakefulness to sleep is a gradual process integrating various viewpoints such as behavior, EEG, physiology and subjective report. Particularly, based on understanding of EEG changes during sleep, SOP has been regarded as a pattern of topographical change in specific frequency and specific state in EEG. Studies on quantitative EEG (qEEG) and event-related potential (ERP) have suggested that SOP shows the changes of functional coordination at the specific cortical areas in qEEG and the changes of regular patterns in response to environmental stimulation in ERP. The development of sleep EEG and topographic mapping of EEG is expected to integrate various viewpoints of SOP and clarify the neurophysiologic mechanism of SOP further.
Electroencephalography ; Evoked Potentials ; Polysomnography ; Wakefulness

Alcohol has extensive effects on sleep and daytime sleepiness. Alcohol has a sleep inducing effect and the effect of increased non-REM sleep and suppressed REM sleep during the first half portion of night sleep, but alcohol induces the effect of decreased non-REM sleep and increased light sleep and frequent awakenings and REM rebound during the second half portion of night sleep. Alcohol provokes chronobiological change such as the changes of amplitude or the phase shifts of hormones or core body temperature. The sleep disruption resulting from alcohol drinking may lead to daytime fatigue and sleepiness. The elderly are at particular in the increased risk of alcohol-related sleep disorders because they achieve higher levels of alcohol in the blood and brain than do younger adults after consuming an equivalent dose. Bedtime alcohol consumption among older adults may lead to unsteadiness if walking is attempted during the night, with increased risk of falls and injuries. Continued alcohol use for sleep induction often induces aggravation of insomnia, alcoholism or sleep related breathing disorders such as obstructive sleep apnea. Alcohol should not be used as substitution of sleep pill because of the dependence and tolerance for sleep inducing effect, and the sleep disruption produced by alcohol withdrawal.
Adult ; Aged ; Alcohol Drinking ; Alcoholism ; Body Temperature ; Brain ; Fatigue ; Humans ; Respiration ; Sleep Apnea, Obstructive ; Sleep Wake Disorders ; Sleep Initiation and Maintenance Disorders ; Sleep, REM ; Walking

OBJECTIVE: Human cerebral hemisphere is known to function asymmetrically with daytime left hemisphere superiority in most right-handed persons. It may have relevance to the localization of specific function of the brain. This study attempted to reveal whether the functional cerebral asymmetry in the wakeful state is still maintained throughout the sleep onset period. METHODS: Thirty-channel EEG was recorded in 61 healthy subjects. The EEG power spectra of each of the seven frequencies were compared between the two kinds of 30-second states; the wakeful stage and the late-sleep stage 1. RESULTS: The asymmetrical indices of sleep stage 1 at several fronto-central leads were decreased in the delta, theta, alpha-2, and all beta bands. Conversely, at parts of parieto-occipital leads showed an increase in the indices of the theta, alphas, beta-1, and beta-2 bands. Any fronto-central leads did not show an increase in the index, and no parieto-occipital leads showed a decrease. CONCLUSION: During the sleep onset period, power spectral asymmetry of the brain showed a different pattern from the wakeful stage. This asymmetrical pattern of EEG powers may suggest a reversal of the left hemispheric dominance during sleep.
Brain* ; Cerebrum ; Electroencephalography ; Healthy Volunteers ; Humans* ; Sleep Stages

OBJECTIVES: Sleep disorders cause changes of autonomic nervous system (ANS) which affect cardiovascular system. Primary insomnia (PI) makes acceleration of sympathetic nervous system (SNS) tone by sleep deficiency and arousal. Obstructive sleep apnea syndrome (OSAS) sets off SNS by frequent arousals and hypoxemias during sleep. We aimed to compare the changes of heart rate variability (HRV) indices induced by insomnia or sleep apnea to analyze for ANS how much to be affected by PI or OSAS. METHODS: Total 315 subjects carried out nocturnal polysomnography (NPSG) were categorized into 4 groups - PI, mild, moderate and severe OSAS. Severity of OSAS was determined by apnea-hypopnea index (AHI). Then we selected 110 subjects considering age, sex and valance of each group's size [Group 1 : PI (mean age=41.50+/-13.16 yrs, AHI <5, n=20), Group 2 : mild OSAS (mean age=43.67+/-12.11 yrs, AHI 5-15, n=30), Group 3 : moderate OSAS (mean age 44.93+/-12.38 yrs, AHI 16-30, n=30), Group 4 : severe OSAS (mean age=45.87+/-12.44 yrs, AHI >30, n=30)]. Comparison of HRV indices among the four groups was performed with ANCOVA (adjusted for age and body mass index) and Sidak post-hoc test. RESULTS: We found statistically significant differences in HRV indices between severe OSAS group and the other groups (PI, mild OSAS and moderate OSAS). And there were no significant differences in HRV indices among PI, mild and moderate OSAS group. In HRV indices of PI and severe OSAS group showing the most prominent difference in the group comparisons, average RR interval were 991.1+/-27.1 and 875.8+/-22.0 ms (p=0.016), standard deviation of NN interval (SDNN) was 85.4+/-6.6 and 112.8+/-5.4 ms (p=0.022), SDNN index was 57.5+/-5.2 and 87.6+/-4.2 (p<0.001), total power was 11,893.5+/-1,359.9 and 18,097.0+/-1,107.2 ms2 (p=0.008), very low frequency (VLF) was 7,534.8+/-1,120.1 and 11,883.8+/-912.0 ms2 (p=0.035), low frequency (LF) was 2,724.2+/-327.8 and 4,351.6+/-266.9 ms2 (p=0.003). CONCLUSIONS: VLF and LF which were correlated with SNS tone showed more increased differences between severe OSAS group and PI group than other group comparisons. We could suggest that severe OSAS group was more influential to increased SNS activity than PI group.
Acceleration ; Anoxia ; Arousal ; Autonomic Nervous System ; Cardiovascular System ; Heart ; Heart Rate ; Polysomnography ; Sleep Apnea Syndromes ; Sleep Apnea, Obstructive ; Sleep Wake Disorders ; Sleep Initiation and Maintenance Disorders ; Sympathetic Nervous System

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*

OBJECTIVES: This study aims to analyze the association between the severity of sleep apnea, sleep and mood related scales, and activity during sleep in obstructive sleep apnea syndrome (OSAS) patients. METHODS: One hundred seventy six drug-free male patients confirmed as OSAS (average age=43+/-11 years) were selected through nocturnal polysomnography (NPSG). OSAS was diagnosed with apnea-hypopnea index (AHI) >5, mean AHI was 39.6+/-26.0. Sleep related scales were Stanford Sleepiness Scale (SSS), Epworth Sleepiness Scale (ESS), Pittsburg Sleep Quality Index (PSQI) and Morningness-Eveningness Scale (MES). Mood related scales were Beck Depression Inventory (BDI), Beck Anxiety Inventory (BAI), State-Trait Anxiety Inventory (STAI) I, II and Profile of Mood States (POMS). NPSG was performed overnight with both wrist actigraphy (WATG). Parameters produced from WATG were total activity score, mean activity score and fragmentation index. We analyzed the correlation between each scale, AHI scored from NPSG and activity score analyzed from WATG. RESULTS: ESS showed significant positive correlation with PSQI, BDI, BAI and STAI I, II, respectively (p<0.01). SSS showed significant positive correlation with PSQI and BAI (p<0.05, p<0.01). BAI showed significant positive correlation with total activity score, mean activity score and fragmentation index (p<0.05, p<0.01, p<0.05). Total activity score showed significant positive correlation with ESS and BAI, respectively (p<0.05). Fragmentation index showed significant positive correlation with ESS, PSQI and BAI (p<0.05, p<0.01, p<0.05). AHI, indicator of sleep apnea is showed no significant correlation with each sleep and mood related scale. CONCLUSION: The degree of daytime sleepiness tends to be associated with night sleep satisfaction, depression and anxiety, and the activity during sleep rather than the severity of sleep apnea.
Actigraphy ; Anxiety ; Depression ; Humans ; Male ; Polysomnography ; Sleep Apnea Syndromes ; Sleep Apnea, Obstructive ; Weights and Measures ; Wrist

OBJECTIVES: Much is still unknown about the neurophysiological mechanisms or dynamics of the sleep onset process. Detrended fluctuation analysis (DFA) is a new tool for the analysis of electroencephalography (EEG) that may give us additional information about electrophysiological changes. The purpose of this study is to analyze long-range correlations of electroencephalographic signals by DFA and their changes in the sleep onset process. METHODS: Thirty channel EEG was recorded in 61 healthy subjects (male : female = 34 : 27, age = 27.2 +/- 3.0 years). The scaling exponents, alpha, were calculated by DFA and compared between four kinds of 30s sleep-wakefulness states such as wakefulness, transition period, early sleep, and late sleep (stage 1). These four states were selected by the distribution of alpha and theta waves in O1 and O2 electrodes. RESULTS: The scaling exponents, alpha, were significantly different in the four states during sleep onset periods, and also varied with the thirty leads. The interaction between the sleep states and the leads was significant. The means (+/- standard deviation) of alphas for the states were 0.94 (+/- 0.12), 0.98 (+/- 0.12), 1.10 (+/- 0.10), 1.07 (+/- 0.07) in the wakefulness, transitional period, early sleep and late sleep state respectively. The mean alpha of anterior fifteen leads was greater than that of posterior fifteen leads, and the two regions showed the different pattern of changes of the alpha during the sleep onset periods. CONCLUSIONS: The characteristic findings in the sleep onset period were the increasing pattern of scaling exponent of DFA, and the pattern was slightly but significantly different between fronto-temporal and parieto-occipital regions. It suggests that the long-range correlations of EEG have a tendency of increasing from wakefulness to early sleep, but anterior and posterior brain regions have different dynamical process. DFA, one of the nonlinear analytical methods for time series, may be a useful tool for the investigation of the sleep onset period.
Brain ; Electroencephalography ; Female ; Humans ; Wakefulness

No abstract available.
Exostoses, Multiple Hereditary* ; Sarcoma, Synovial*

OBJECTIVE: The purpose of this study was to identify the regions of the brain associated with recurrent nocturnal chronic hypoxic episodes in patients with untreated obstructive sleep apnea syndrome (OSAS) using low-resolution electromagnetic tomography (LORETA) and quantitative electroencephalography (QEEG). METHODS: Nocturnal polysomnograph (NPSG) and subsequent morning electroencephalograph (EEG) were measured in 20 subjects with OSAS. Mild (n=10 ages 39.5+/-12.1 years) and severe (n=10 ages 41.7+/-13.6 years) right-handed male OSAS subjects were selected by interview and questionnaires including the NPSG, Beck Depression Inventory, Beck Anxiety Inventory, Epworth Sleepiness Scale, and Pittsburgh Sleep Quality Index. The LORETA and QEEG were compared between the severe and mild OSAS groups by frequency bands (delta 1-3 Hz, theta 4-7 Hz, alpha 8-12 Hz, beta1 13-18 Hz, beta2 19-21 Hz, beta3 22-30 Hz, and total 1-30 Hz) made by spectral analysis during resting with the eyes closed. RESULTS: The LORETA analysis showed decreased alpha activity at the right posterior cingulate gyrus (Brodmann area 23) in cases with severe OSAS compared to mild OSAS (p<0.05). For the QEEG, the absolute power of the alpha activity (8-12 Hz) was decreased in P3 (p=0.047), PZ (p=0.039) and O2 (p=0.04) in cases with severe OSAS compared to mild OSAS cases. The LORETA and QEEG analyses had similar results with regard to band, activation and location. CONCLUSION: The decreased activity of the alpha frequency in the right posterior cingulate gyrus, in patients with severe OSAS compared to those with mild OSAS, suggests that chronic repeated short-term hypoxia during sleep, in OSAS, could provoke cortical brain dysfunction associated with cognitive dysfunction such as memory and attention.
Anoxia ; Anxiety ; Brain ; Depression ; Electroencephalography ; Gyrus Cinguli ; Humans ; Hypoxia, Brain ; Magnets* ; Male ; Memory ; Surveys and Questionnaires ; Sleep Apnea, Obstructive*

OBJECTIVES: It is well established that primary insomnia affects the activity of autonomic nervous system. We tried to know how the activity of autonomic nervous system during night sleep changes by analyzing correlation between heart rate variability (HRV) index and the variables related with sleep structure in primary insomnia. METHODS: Thirty three subjects (mean age:36.2+/-14.2 years, male:female=15:18) who were diagnosed with primary insomnia were selected for the study. Nocturnal polysomnography (NPSG) was carried out on each subject and correlation was analyzed between high frequency/low frequency ratio (LF/HF ratio), one of HRV indices and the variables related with sleep structure which were calculated from NPSG. RESULTS: When age and sex were controlled, LF/HF ratio showed negative correlations with slow wave sleep and stage 2 sleep, respectively (r(p)=-0.43, p=0.01;r(p)=-0.37, p=0.04). On the other hands LF/HF ratio showed a positive correlation with arousal index (r(p)=0.65, p<0.001). The activity of autonomic nervous system responded differentially depending on the change of sleep structure in primary insomnia. Especially the increase of arousal index and the decrease of slow wave sleep and stage 2 sleep which are the components of non-REM sleep provoked hyperactivity of sympathetic nervous system. CONCLUSION: This study suggests that the typical change of sleep structure in primary insomnia can negatively impact on cardiovascular system.
Arousal ; Autonomic Nervous System ; Cardiovascular System ; Hand ; Heart ; Heart Rate ; Polysomnography ; Sleep Initiation and Maintenance Disorders