Humans ; Sleep, REM ; Memory ; Sleep ; REM Sleep Behavior Disorder

INTRODUCTION: It has been proposed that narcolepsy and REM sleep behavior disorder (RBD) have overlapped symptom profile and pathophysiology. This study was aimed at measuring and comparing changes in EEG frequency band of REM sleep in narcolepsy and RBD, applying EEG spectral analysis method. METHODS: Nine patients diagnosed as narcolepsy and the same number of RBD patients were studied. Spectral analysis of the REM sleep EEG was performed in each patient on 9 epochs selected evenly from the first, second, and third REM periods. Then, we compared frequency band percentages of REM sleep EEG in narcolepsy and RBD. RESULTS: Narcolepsy patients had significantly higher delta frequency ratio than RBD ones (p=0.00). In alpha and beta2 frequency bands, RBD patients showed higher percentage than narcolepsy ones. Slow wave sleep was more prevalent in narcolepsy patients. But, no difference of REM sleep percentage was found between the two groups (p=0.93). CONCLUSION: Higher delta frequency ratio in REM sleep of narcolepsy patients than RBD ones reflects that sleep-promoting mechanism is more dominant in narcolepsy than in RBD.
Electroencephalography ; Humans ; Narcolepsy ; REM Sleep Behavior Disorder ; Sleep, REM

INTRODUCTION: Detrended fluctuation analysis (DFA) is used as a way of studying nonlinearity of EEG. In this study, DFA is applied on sleep EEG of normal subjects to look into its nonlinearity in terms of EEG channels and sleep stages. METHOD: Twelve healthy young subjects (age: 23.8+/-2.5 years old, male:female=7:5) have undergone nocturnal polysomnography (nPSG). EEG from nPSG was classified in terms of its channels and sleep stages and was analyzed by DFA. Scaling exponents (SEs) yielded by DFA were compared using linear mixed model analysis. RESULTS: Scaling exponents (SEs) of sleep EEG were distributed around 1 showing long term temporal correlation and self-similarity. SE of C3 channel was bigger than that of O1 channel. As sleep stage progressed from stage 1 to slow wave sleep, SE increased accordingly. SE of stage REM sleep did not show significant difference when compared with that of stage 1 sleep. CONCLUSION: SEs of Normal sleep EEG showed nonlinear characteristic with scale-free fluctuation, long-range temporal correlation, self-similarity and self-organized criticality. SE from DFA differentiated sleep stages and EEG channels. It can be a useful tool in the research with sleep EEG.
Electroencephalography* ; Polysomnography ; Sleep Stages ; Sleep, REM

The reciprocal interaction between sleep and pain has been reported by numerous studies. Patients with acute or chronic pain often complain of difficulty falling asleep, frequent awakenings, shorter sleep duration, unrefreshing sleep, and poor sleep quality in general. According to the majority of the experimental human studies, sleep deprivation may produce hyperalgesic changes. The selective disruption of slow wave sleep has shown this effect more consistently, while results after selective REM sleep deprivation remain unclear. Patients with chronic pain have a marked alteration of sleep structure and continuity, such as frequent sleep-stage shifts, increased nocturnal awakenings, decreased slow wave sleep (SWS), decreased rapid eye movement (REM) sleep, and alpha-delta sleep. Many analgesic medications can alter sleep architecture in a manner similar to the effects of acute and chronic pain, suppressing SWS and REM sleep.
Chronic Pain ; Humans ; Sleep Deprivation ; Sleep, REM

OBJECTIVES: The dream recall and sleep of patients with rapid eye movement sleep behavior disorder (RBD) were not sufficiently studied. We hypothesized that RBD patients have frequent dream recall with poor sleep quality, and investigated the relationship between the dream recall frequency and sleep quality in RBD patients compared to controls. METHODS: We analyzed 81 drug naïve patients [RBD (+), 64.6±8.3 y, 57 males] and 81 age and gender matched patients with sleep disturbances without RBD [RBD (−), 63.7±7.3 y, 57 males]. All completed Pittsburgh sleep quality index (PSQI), insomnia severity index (ISI), Epworth sleepiness scale and Beck depression inventory. The 5-point rating scale was used to categorize dream recall frequency of most recent month (0=never, 4=very frequent). RESULTS: In RBD (+), dream recall frequency was much higher [frequent dreaming, 77.2% vs. 35.4%], and subjective sleep quality was much better [PSQI, 6.36±3.26 vs. 8.71±4.69]. Insomnia severity was much less in RBD (+) (ISI, 9.13±5.86) than RBD (−) (12.43±7.62). No significant differences were found in sleep parameters except lower N2 sleep % in RBD (+). The relationship between dream recall frequency and sleep was not significant in RBD (+), yet, a positive correlation was noted in RBD (−). CONCLUSIONS: RBD (+) had better sleep quality despite higher frequency of dream recall compared to RBD (−). Also dream recall was not related to their sleep quality in RBD (+), which suggests that RBD patients may have different sleep perception about their sleep and sleep quality.
Depression ; Dreams ; Humans ; REM Sleep Behavior Disorder ; Sleep Initiation and Maintenance Disorders ; Sleep, REM

Study in the field of sleep and memory has greatly expanded recently and the number of publications supporting the association between sleep and memory consolidation is rapidly growing. This study presents evidence related to sleep-dependent memory consolidation, ranging from behavioral task-performing studies to molecular studies, and several arguments against the association. Basic researches show that many genes are upwardly regulated during sleep and patterns of brain activation seen during daytime task training are repeated during subsequent REM sleep. Several electrophysiological studies demonstrate the correlation between spindle density increase following training and subsequent improvement in performing the training task. Overnight improvement or deterioration in task performance correlates with REM or SWS sleep. In the end, a lot of issues remain to be studied and discussed further in the future in spite of supporting evidence now available.
Brain ; Memory* ; Sleep, REM ; Task Performance and Analysis

Saccades are rapid eye movements that shift the line of sight between successive points of fixation. The cerebellum calibrates saccadic amplitude (dorsal vermis and fastigial nucleus) and the saccadic pulse-step match (flocculus) for optimal visuo-ocular motor behavior. Based on electrophysiology and the pharmacological inactivation studies, early activity in one fastigial nucleus could be important for accelerating the eyes at the beginning of a saccade, and the later activity in the other fastigial nucleus could be critical for stopping the eye on target, which is controlled by inhibitory projection from the dorsal vermis. The cerebellum could monitor a corollary discharge of the saccadic command and terminate the eye movement when it is calculated to be on target. The fastigial nucleus and dorsal vermis also participate in the adaptive control of saccadic accuracy.
Cerebellum ; Electrophysiology ; Eye Movements ; Saccades* ; Sleep, REM

OBJECTIVE: This study was designed to investigate 1) sleep changes after antidepressant(dothiepin) treatment, and 2) sleep variables which seem to be associated with clinical response in the depressed patients. METHODS: The subjects consisted of 16 patients who fullfilled the criteria for major depression by the Diagnostic and Statistical Manual,(4th edition). Their sleep was recorded using polysomnography at the baseline and after one week and three weeks of dothiepin treatment. All subjects were further interviewed using Hamilton Rating Scale for Depression (HRSD) to rate the severity of their depression. High response to the drug was defined as a reduction of more than 50% of the HRSD score. Result : The results were as follows : 1) Depressed patients after dothiepin treatment showed more total sleep time(p=0.019), shorter sleep latency(p=0.05), less awake time(p=0.033), more sleep efficiency(p=0.018), more stage 2 sleep(p=0.002), less REM time(p=0.000), and longer REM sleep latency(p=0.004) than before treatment. 2) There were no differences in sleep variables between those who received 1 week and 3 weeks of dothiepin treatment except of th shortening of sleep latency after 3 weeks(p<0.05). 3) Depressive symptom scores on HRSD were reduced after 1 week and 3 weeks of dothiepin treatment as compared with the baseline. 4) High responers showed a tendency of increased wake time(p=0.054), while their stage 4 sleep decreased after 1 week of dothiepin treatment as compared with the low responders(p=0.0136). Conclusions : These results suggest that sleep of the depressed patients after dothiepin treatment tends to be nomalized and sleep chages seem to appear early in the treatment phase. In addition, clinical response might be associated with greater wake time at the baseline and lesser atage 4 sleep 1 week of dothiepin treatment.
Depression ; Dothiepin ; Humans ; Polysomnography ; Sleep, REM

We analyzed interictal spikes of complex partial seizure by two parameters of sleep structure. They are macrostrure and microstructure of sleep. The macrostructure of sleep is traditional parameter and includes REM and NREM sleep. The microstructure of sleep is recently identified modalities of arousal control during NREM sleep: (a) the cyclic alternating pattern (CAP) expressed by alternating and successive phasic fluctuation of sleep; and (b) non-CAP(NCAP) characterized by prolonged stable periods of EEG. We performed polygraphical analysis of extended daytime-sleep of eight patients with complex partial seizure. The mean spike index(SI) was 4.9+3.6. The percentage of CAP time in total NREM was 50.7+5.8 and phase A in CAP time was 32.5+4.2. Significant increase in discharge rates was observed in NREM compared with REM sleep (psleep with repect to superficial sleep (p>O. 05). Spiking activities were significantly enhanced during CAP sleep. Patients showed significant SI differences between CAP and NCAP sleep (psleep (p Arousal ; Electroencephalography ; Humans ; Seizures* ; Sleep, REM

OBJECTIVE: Light pollution has become a social and health issue. We performed an experimental study to investigate impact of dim light at night (dLAN) on sleep in female subjects, with measurement of salivary melatonin. METHODS: The 25 female subjects (Group A: 12; Group B: 13 subjects) underwent a nocturnal polysomnography (NPSG) session with no light (Night 1) followed by an NPSG session randomly assigned to two conditions (Group A: 5; Group B: 10 lux) during a whole night of sleep (Night 2). Salivary melatonin was measured before and after sleep on each night. For further investigation, the female and male subjects of our previous study were collected (48 subjects), and differences according to gender were compared. RESULTS: dLAN during sleep was significantly associated with decreased total sleep time (TST; F=4.818, p=0.039), sleep efficiency (SE; F=5.072, p=0.034), and Stage R latency (F=4.664, p=0.041) for female subjects, and decreased TST (F=14.971, p<0.001) and SE (F=7.687, p=0.008), and increased wake time after sleep onset (F=6.322, p=0.015) and Stage R (F=5.031, p=0.03), with a night-group interaction (F=4.579, p=0.038) for total sample. However, no significant melatonin changes. There was no significant gender difference of the impact of dLAN on sleep, showing the negative changes in the amount and quality of sleep and the increase in rapid eye movement (REM) sleep in the both gender group under 10 lux condition. CONCLUSION: We found a negative impact of exposure to dLAN on sleep in female as well as in merged subjects. REM sleep showed a pronounced increase under 10 lux than under 5 lux in merged subjects, suggesting the possibility of subtle influences of dLAN on REM sleep.
Female* ; Humans ; Male* ; Melatonin ; Polysomnography ; Sleep, REM