Rapid Eye Movement Sleep Periods Research Articles

Polysomnographic features prior to dream enactment behaviors in isolated rapid eye movement sleep behavior disorder

ObjectiveThis study aimed to identify electroencephalogram correlates of dream enactment behaviors (DEBs) and elucidate their cortical dynamics in patients with isolated/idiopathic rapid eye movement (REM) sleep behavior disorder (iRBD). MethodsThis cross-sectional study included 15 patients with iRBD. Two REM sleep periods in routine polysomnography were compared: the 60 s preceding the DEBs (“pre-representative behavior” [preR]), and the 60 s with the least submental electromyogram activity (“background” [BG]). Six EEG frequency bands and electrooculogram were analyzed; power spectra, coherence and phase-locking values in four 15-s periods were examined to assess trends. These indices were also compared between preR and BG. ResultsCompared with BG, significantly higher delta power in the F3 channel and gamma power in the F4 and O2 channels were observed during preR. For functional connectivity, the widespread beta-band connectivity was significantly increased during preR than BG. ConclusionBefore notable REM sleep behaviors, uneven distributed higher EEG spectral power in both very low and high frequencies, and increased wide-range beta band functional connectivity, were observed over 60 s, suggesting cortical correlates to subsequent DEBs. SignificanceThis study may shed light on the pathological mechanisms underlies RBD through the routine vPSG analysis, leading to detection of DEBs.

1000 Hypnagogic hallucinations as a manifestation of Parkinson’s disease

Abstract Introduction Narcolepsy and Parkinson’s disease (PD) share many similar symptoms. Narcolepsy is characterized by excessive daytime sleepiness, sleep attacks, sleep paralysis, and hallucinations, with or without cataplexy. Hypnagogic hallucinations occur while falling asleep and the person experiencing them typically knows they are not real. Here, we present a case of hypnagogic hallucinations as a manifestation of PD in a patient without narcolepsy. Report of case(s) A 66-year-old female with a history of tremor was seen in the sleep disorders clinic with chief complaints of dream enactment and excessive daytime sleepiness. She described bruising after falling out of bed. On further questioning, she reported instances of seeing “death and a grim reaper as well as a dark figure”, usually upon falling asleep at night. She denied daytime hallucinations. She underwent diagnostic polysomnography (PSG), which showed mild obstructive sleep apnea and loss of rapid eye movement (REM) atonia during brief periods of REM sleep. Treatment for dream enactment was implemented by increasing her dose of melatonin (which she had been taking for insomnia) and initiation of clonazepam, which led to significant improvement in dream enactment. Over the next two years, she was diagnosed with PD and started on carbidopa-levodopa. She reported more frequent hypnagogic hallucinations during a follow-up visit, occurring 1-2 times weekly, which her neurologist attributed to being on higher dosages of dopaminergic therapy. During a recent visit, she reported no dream enactment and infrequent hypnagogic hallucinations. Conclusion Sleep disturbances in PD are common and include insomnia, hypersomnia, and REM behavioral disorder (RBD). A lesser appreciated association is that between hypnagogic hallucinations and PD, as depicted in this case. Partial hypocretin cell loss in PD has been postulated to result in disturbed hypocretin signaling, which probably explains the occurrence of narcolepsy-like symptoms (including hypnagogic hallucinations) in PD. Hypnagogic hallucinations are more common among patients with PD compared to the general population and tend to occur more as PD progresses, with longer duration of treatment with dopaminergic agents, with older age, and in patients with RBD. This case serves as an important reminder that hypnagogic hallucinations are not pathognomonic for narcolepsy and are likely underappreciated in PD. Support (if any)

A Narrative Review on REM Sleep Deprivation: A Promising Non-Pharmaceutical Alternative for Treating Endogenous Depression.

Endogenous depression represents a severe mental health condition projected to become one of the worldwide leading causes of years lived with disability. The currently available clinical and non-clinical interventions designed to alleviate endogenous depression-associated symptoms encounter a series of inconveniences, from the lack of intervention effectiveness and medication adherence to unpleasant side effects. In addition, depressive individuals tend to be more frequent users of primary care units, which markedly affects the overall treatment costs. In parallel with the growing incidence of endogenous depression, researchers in sleep science have discovered multiple links between rapid eye movement (REM) sleep patterns and endogenous depression. Recent findings suggest that prolonged periods of REM sleep are associated with different psychiatric disorders, including endogenous depression. In addition, a growing body of experimental work confidently describes REM sleep deprivation (REM-D) as the underlying mechanism of most pharmaceutical antidepressants, proving its utility as either an independent or adjuvant approach to alleviating the symptoms of endogenous depression. In this regard, REM-D is currently being explored for its potential value as a sleep intervention-based method for improving the clinical management of endogenous depression. Therefore, this narrative review represents a comprehensive inventory of the currently available evidence supporting the potential use of REM-D as a reliable, non-pharmaceutical approach for treating endogenous depression, or as an adjuvant practice that could improve the effectiveness of currently used medication.

SSAVE: A tool for analysis and visualization of sleep periods using electroencephalography data.

Human sleep architecture is structured with repeated episodes of rapid-eye-movement (REM) and non-rapid-eye-movement (NREM) sleep. An overnight sleep study facilitates identification of macro and micro changes in the pattern and duration of sleep stages associated with sleep disorders and other aspects of human mental and physical health. Overnight sleep studies record, in addition to electroencephalography (EEG) and other electro-physiological signals, a sequence of sleep-stage annotations. SSAVE, introduced here, is open-source software that takes sleep-stage annotations and EEG signals as input, identifies and characterizes periods of NREM and REM sleep, and produces a hypnogram and its time-matched EEG spectrogram. SSAVE fills an important gap for the rapidly growing field of sleep medicine by providing an easy-to-use tool for sleep-period identification and visualization. SSAVE can be used as a Python package, a desktop standalone tool or through a web portal. All versions of the SSAVE tool can be found on: https://manticore.niehs.nih.gov/ssave.

Detection of rapid eye movement sleep period in EEG signals using wavelet modifications

The aim of the present research was to examine the electrical activity of the brain on polysomnographic recordings using a new approach of oscillatory wavelet patterns. This study has shown that EEG signals recorded in the REM stage of sleep have specific oscillatory characteristics in the band 20-40 Hz, which make it possible to statistically reliably distinguish this stage of sleep both from other stages of sleep and from wakefulness. Keywords: continuous wavelet analysis, polysomnography, sleep stages.

Respiration and rapid eye movement (REM) sleep substructure: short versus long episodes.

Rapid eye movement (REM) sleep in rodents is defined by the presence of theta rhythm in the absence of movement. The amplitude and frequency of theta oscillations have been used to distinguish between tonic and phasic REM sleep. However, tonic REM sleep has not been further subdivided, although characteristics of network oscillations such as cross-frequency coupling between theta and gamma vary within this sub-state. Recently, it has been shown that theta-gamma coupling depends on an optimal breathing rate of ~5 Hz. The frequency of breathing varies strongly throughout REM sleep, and the duration of single REM sleep episodes ranges from several seconds to minutes, whereby short episodes predominate. Here we studied the relation between breathing frequency, accelerometer activity, and the length of REM sleep periods. We found that small movements detected with three-dimensional accelerometry positively correlate with breathing rate. Interestingly, breathing is slow in short REM sleep episodes, while faster respiration regimes exclusively occur after a certain delay in longer REM sleep episodes. Thus, merging REM sleep episodes of different lengths will result in a predominance of slow respiration due to the higher occurrence of short REM sleep periods. Moreover, our results reveal that not only do phasic REM sleep epochs predominantly occur during long REM sleep episodes, but that the long episodes also have faster theta and higher gamma activity. These observations suggest that REM sleep can be further divided from a physiological point of view depending on its duration. Higher levels of arousal during REM sleep, indicated by higher breathing rates, can only be captured in long REM sleep episodes.

Effects of Continuous Positive Airway Pressure Therapy on Nocturnal Blood Pressure Fluctuation Patterns in Patients with Obstructive Sleep Apnea.

This retrospective study was designed to evaluate the effects of continuous positive airway pressure (CPAP) therapy, a well-established treatment for obstructive sleep apnea (OSA), on nocturnal blood pressure fluctuations (NBPFs) during rapid eye movement (REM) and non-REM sleep, and to evaluate the NBPF patterns in patients with OSA. We included 34 patients with moderate-to-severe OSA who underwent polysomnography using pulse transit time before and at 3–6 months after CPAP therapy. Nocturnal BP and NBPF frequency in REM and non-REM sleep were investigated, as well as NBPF pattern changes after receiving CPAP therapy. CPAP therapy resulted in significant reductions in the apnea–hypopnea index (AHI), arousal index, nocturnal systolic and diastolic BP, and NBPF frequency in REM and non-REM sleep (all p < 0.01). A higher AHI before CPAP resulted in lower nocturnal systolic BP (r = 0.40, p = 0.019) and NBPFs (r = 0.51, p = 0.002) after CPAP. However, 58.8% of patients showed no change in NBPF patterns with CPAP therapy. CPAP therapy significantly improved almost all sleep-related parameters, nocturnal BP, and NBPF frequency in REM and non-REM sleep periods, but NBPF patterns showed various changes post-CPAP therapy. These results suggest that factors other than OSA influence changes in NBPF patterns.

The REM-sleep-related characteristics of narcolepsy: a nation-wide multicenter study in Turkey, the REMCON study

IntroductionNarcolepsy type 1 (NT1) is caused by hypocretin deficiency, the pathophysiology of narcolepsy type 2 (NT2) has not been delineated. Except for the hypocretin deficiency and cataplexy, all clinical and laboratory features used in the diagnosis of NT2 are identical to those used for NT1. The aim of this study was to assess the rapid eye movement (REM) sleep-related characteristics in the patients with narcolepsy; the characteristics of REM sleep in polysomnography (PSG) and multiple sleep latency test (MSLT) recordings, the quantification of REM sleep without atonia (RSWA) and atonia index, and the analysis of rapid eye movements (REMs) during REM sleep. Materials and methodsThis study was planned by the Sleep Medicine Study Group of the Turkish Neurology Society, and conducted in 11 centers in eight cities in Turkey. The analysis of RSWA was analyzed by reviewing all REM sleep periods on nocturnal PSG and MSLT recordings per standard criteria. The total duration of the increased muscle tone during REM sleep in the chin and bilateral leg electromyography (EMG) recordings was calculated as RSWA index. The REMs index was also investigated the relation to the RSWA. ResultsA total of 274 patients were involved; 147 patients (53.6%) were males and 127 patients (46.4%) were females; the mean age was 29.1 ± 12.0 years. The diagnosis of NT1 was made in 166 patients (60.6%), and 108 patients (39.4%) were diagnosed as having NT2. The mean Epworth sleepiness scale score was significantly higher in patients with NT1 than the patients with NT2 (P = 0.001). The diagnosis of REM sleep behavior disorder (RBD) was made in 19.3% of the patients with NT1 versus in 2.8% of the patients with NT2 (P < 0.001). The percentage of SOREMP in PSG recordings was significantly higher in patients with NT1 (37.1%) than those with NT2 (18.9%, P = 0.001). MSLT showed that the mean sleep latency was shorter in patients with NT1 compared to those with NT2 (P < 0.001). The total duration of REMs on electrooculography recordings was also significantly higher in patients with RSWA in comparison with the patients without RSWA (P = 0.002). Total duration of REMs was significantly and positively correlated with the duration of RSWA on chin-EMG and leg-EMG recordings (P = 0.001). ROC analyses showed an RSWA index of ≥2% for the RSWA on chin-EMG with a sensitivity of 86.7% and a specificity of 71.3% (P < 0.001). The REMs index ≥20% was associated with the presence of RSWA with a sensitivity of 70.0% and a specificity of 57.1% (P = 0.008). ConclusionsIn this nation-wide study, we identified for the first time that the increase in REMs density during REM sleep may be a major correlate of the RSWA. Significant positive correlations were demonstrated between the total duration of REMs on electrooculography recordings and the mean durations of RSWA in both chin and leg EMG recordings. A REMs index of >20% was demonstrated to have a moderate sensitivity and specificity in the diagnosis of RSWA. As observed in chin RSWA index, REMs index also showed a significantly high association with RBD, in comparison to RSWA per standard criteria.

Automatic analysis of muscular activity in the flexor digitorum superficialis muscles: a fast screening method for rapid eye movement sleep without atonia.

To identify a fast and reliable method for rapid eye movement (REM) sleep without atonia (RWA) quantification. We analyzed 36 video-polysomnographies (v-PSGs) of isolated REM sleep behavior disorder (iRBD) patients and 35 controls' v-PSGs. Patients diagnosed with RBD had: i) RWA, quantified with a reference method, i.e. automatic and artifact-corrected 3-s Sleep Innsbruck Barcelona (SINBAR) index in REM sleep periods (RSPs, i.e. manually selected portions of REM sleep); and ii) v-PSG-documented RBD behaviors. We quantified RWA with other (semi)-automated methods requiring less human intervention than the reference one: the indices proposed by the SINBAR group (the 3-s and 30-s phasic flexor digitorum superficialis (FDS), phasic/"any"/tonic mentalis), and the REM atonia, short and long muscle activity indices (in mentalis/submentalis/FDS muscles). They were calculated in whole REM sleep (i.e. REM sleep scored following international guidelines), in RSPs, with and without manual artifact correction. Area under curves (AUC) discriminating iRBD from controls were computed. Using published cut-offs, the indices' sensitivity and specificity for iRBD identification were calculated. Apnea-hypopnea index in REM sleep (AHIREM) was considered in the analyses. RWA indices from FDS muscles alone had the highest AUCs and all of them had 100% sensitivity. Without manual RSP selection and artifact correction, the "30-s phasic FDS" and the "FDS long muscle activity" had the highest specificity (85%) with AHIREM < 15/h. RWA indices were less reliable when AHIREM≥15/h. If AHIREM<15/h, FDS muscular activity in whole REM sleep and without artifact correction is fast and reliable to rule out RWA.

Rapid eye movement predominant obstructive sleep apnoea: prognostic relevance and clinical approach.

Rapid eye movement (REM) obstructive sleep apnoea (OSA) is a stage-specific OSA, in which obstructive events occur primarily during REM sleep. This review discusses REM-OSA definitions, its cardiometabolic correlates, associated comorbidities and treatment, and addresses diagnostic ambiguities and therapeutic pitfalls. Current evidence indicates that REM-OSA is prevalent among younger age groups and women and is independently associated with cardiometabolic complications, particularly hypertension, metabolic complications such as insulin resistance and metabolic syndrome. However, currently, there is no consensus on the accepted diagnostic criteria for REM-OSA. Available data suggest that adherence to positive airway pressure (PAP) therapy in patients with REM-OSA is suboptimal. Moreover, the currently accepted criteria for good adherence to PAP therapy of 4 h/night, 70% of the days may not be suitable for REM-OSA, as it will not cover most of the REM sleep periods. In addition, further research is needed to assess the impact of REM-OSA treatment on cardiometabolic outcomes. Patients with REM-OSA are at an increased risk of cardiometabolic complications. A high index of suspicion is needed to diagnose this disorder, and close follow-up is required to enhance adherence to therapy.

Objective rapid eye movement sleep characteristics of recurrent isolated sleep paralysis: a case-control study.

Recurrent isolated sleep paralysis (RISP) is a rapid eye movement (REM) parasomnia characterized by a dissociative state with characteristics of REM sleep and wakefulness. Pathophysiology has not yet been clarified and very little research has been performed using objective polysomnographic measures with inconsistent results. The main aim of our study was to find whether higher REM sleep fragmentation is consistent with the theory of state dissociation or whether signs of dissociation can be detected by spectral analysis. A total of 19 participants in the RISP group and 19 age- and gender-matched participants in the control group underwent two consecutive full-night video-polysomnography recordings with 19-channel electroencephalography. Apart from sleep macrostructure, other REM sleep characteristics such as REM sleep arousal index, percentage of wakefulness and stage shifts within REM sleep period were analyzed, as well as power spectral analysis during REM sleep. No difference was found in the macrostructural parameters of REM sleep (percentage of REM sleep and REM latency). Similarly, no significant difference was detected in REM sleep fragmentation (assessed by REM sleep arousal index, percentage of wakefulness and stage shifts within REM sleep). Power spectral analysis showed higher bifrontal beta activity in the RISP group during REM sleep. The results showed an underlying persistent trait of higher cortical activity that may predispose patients with sleep paralysis to be more likely to experience recurrent episodes, without any apparent macrostructural features including higher REM sleep fragmentation.

Factors related to oxygen desaturation index during sleep 7days after bilateral sagittal splitting ramus osteotomy in patients without previous obstructive sleep apnea.

The incidence of obstructive sleep apnea (OSA) immediately after surgery in patients with dentofacial deformities without previous OSA remains unknown. We aimed to perioperatively evaluate factors associated with oxygen desaturation index (ODI) during sleep, 7days after bilateral splitting ramus osteotomy (BSSRO) in patients without previous OSA. Fifty-one patients (15 males, 36 females) with dentofacial deformities, scheduled to undergo BSSRO, were included. Polysomnography was performed before orthognathic surgery. Perioperative OSA was evaluated with peripheral arterial tonometry on the day of surgery and 1, 2, 3, 4, and 7days postoperatively. Rapid eye movement (REM) sleep periods and the ODI were measured. Factors associated with perioperative ODI after surgery were statistically analyzed. REM sleep periods were significantly decreased on the day of surgery and significantly increased at 4 and 7days postoperatively, compared to the preoperative period. ODI increased on the day of surgery, decreased after 1day, and increased again at 4 and 7days postoperatively. ODI on the day of surgery was significantly increased due to increased preoperative ODI, overjet, and SN-MP angle and decreased SNA and SNB angle. ODI at 7days postoperatively was significantly increased due to increased REM sleep periods and decreased SN-MP and gonial angle. ODI was increased in response to REM sleep periods 7days after BSSO. Airway management in patients with dentofacial deformity should be given more attention by preoperative assessment for OSA, even in the absence of previous OSA, until 7days postoperatively due to REM rebound.

Determination of the sleep-wake pattern and feasibility of NREM/REM discrimination using the non-invasive piezoelectric system in rats.

The piezoelectric cage-floor sensors have been used to successfully dissect sleep patterns in mice based on signal features related to respiration and body movements. We studied performance of the piezoelectric system to quantify the sleep-wake pattern in the rat over 7days of recording compared with a visual electroencephalogram/electromyogram scoring, and under two light/dark (LD12:12 and LD16:8) photoperiods leading to change in the 24-hr sleep characteristics (N=7 per group). The total sleep time (%/24hr) over the 7days recording and hourly sleep time over the last 24-hr recording were not statistically different between methods under the two photoperiods. Both methods detected higher total sleep time with the LD16:8 photoperiod compared with LD12:12 (p<.05), and correlated significantly (p<.001) at light and dark periods during each photoperiod. The accuracies for discrimination of sleep-wake patterns between methods were 81.9% and 84.9% for LD12:12 and LD16:8, respectively. In addition, spectral analysis of the respiratory signal given by piezo during all 10-s periods of the corresponding non-rapid eye movement and rapid eye movement sleep periods recorded by electroencephalogram/electromyogram resulted in selection of 36 features that could be inserted in an automated non-rapid eye movement sleep and rapid eye movement sleep classification, with 90% accuracy with the electroencephalogram/electromyogram visual scoring. The piezo system proved to be a reliable non-invasive alternative to electroencephalogram recording to study total sleep time in rat, with feasibility to discriminate between non-rapid eye movement and rapid eye movement sleep stages. This will be interesting in pharmacological or bio-behavioural studies evaluating sleep patterns or the restorative functions of sleep in the body and the brain.

411 REM predominance of OSA: Associated with supine position, but not with CPAP adherence

Abstract Introduction Obstructive sleep apnea (OSA) is a heterogeneous disease dependent on many factors including the sleep stage and the body position. OSA is often more severe during the rapid eye movement (REM) sleep stage, a phenomenon known as REM predominance. Prior studies suggested associations of higher REM predominance of OSA with younger age, higher obesity, and lower adherence to continuous positive airway pressure (CPAP) therapy, but these studies had small cohort sizes. Here we leverage home-based sleep tests (HST) that estimate REM sleep and measure body position to study REM predominance in a larger cohort of OSA patients. Methods We retrospectively reviewed patients who took HST at our clinic using devices based on peripheral arterial tonometry (WatchPAT, Itamar Medical). The HST results included estimated REM sleep periods and measured body positions. Auto-titrating CPAP therapy was prescribed for the majority of OSA patients diagnosed by the HST. Our inclusion criteria were: apnea-hypopnea index (AHI) above 5 /hour, estimated REM sleep time above 30 minutes, oxygen saturation below 90% (T90) for less than 10 minutes, and successful retrieval of CPAP usage data. CPAP adherence was defined as the percentage of nights with CPAP usage above four hours, and REM predominance as the ratio between REM AHI and non-REM AHI. Additionally, the percentage of estimated sleep time in supine position was calculated. Results Among 292 consecutive patients whose HST were reviewed, 113 patients met the inclusion criteria. The 25th-75th percentile ranges of age, body mass index (BMI), AHI, REM predominance, CPAP adherence and supine sleep percentage were 36–56 years, 28.1–38.4 kg/m2, 8.9–25.9 /hour, 1.27–2.89, 40%-97% and 28%-72%, respectively. REM predominance was not associated with CPAP adherence (P &amp;gt; 0.05), but was significantly associated with lower age, higher BMI, and higher supine sleep percentage (all P &amp;lt; 0.01). Conclusion We found that REM-predominant OSA is relatively more prevalent not only in young and obese patients, but in patients who sleep relatively more in the supine position. This association of REM predominance with body position is a novel finding to our knowledge. Contrary to prior studies, we did not find association of REM predominance with adherence to CPAP therapy. Support (if any):

Nocturnal Sleep Onset Rapid Eye Movement Sleep Periods as a Predictor of the Severity of Narcolepsy in Korea

Nocturnal Sleep Onset Rapid Eye Movement Sleep Periods as a Predictor of the Severity of Narcolepsy in Korea

Differential Effects of REM Sleep on Emotional Processing: Initial Evidence for Increased Short-term Emotional Responses and Reduced Long-term Intrusive Memories

ABSTRACT Background: Rapid eye movement (REM) sleep has been postulated to facilitate emotional processing of negative stimuli. However, empirical evidence is mixed and the conditions under which higher amounts of REM sleep lead to decreased or increased emotional responses are unclear. We proposed that the time course between REM sleep and measurement of emotional responses is a crucial factor and hypothesized that more REM sleep will enhance emotional responses shortly after sleep, but will lead to decreased emotional responses in the long-term. Participants and Methods: Seventy-six healthy young women watched negative and neutral pictures before a polysomnographically-recorded nap including three different groups (1: no REM sleep, 2: REM sleep awakening, 3: REM sleep). Short-term emotional responses were measured using aversiveness ratings of negative pictures; aversiveness ratings of intrusive picture memories on the three subsequent evenings were used to measure long-term emotional responses. Results: For short-term emotional responses, no significant interaction indicating group differences was found. However, we found correlations between longer REM sleep duration and higher aversiveness ratings of negative pictures. In contrast, lower aversiveness of intrusive picture memories after two days was found in participants with a full REM sleep period compared to individuals without REM sleep. Correlational analyses also supported this pattern of results. Conclusions: Results suggest that REM sleep may increase reactivity to emotional stimuli in the short-term and this effect of REM sleep appears to facilitate emotional processing during subsequent nights leading to reduced intrusive picture memories in the long-term.

Finger Twitches are More Frequent in REM Sleep Than in Non-REM Sleep.

IntroductionAbnormal rapid eye movement (REM) sleep is often symptomatic of chronic disorders, however polysomnography, the gold standard method to measure REM sleep, is expensive and often impractical. Attempts to develop cost-effective ambulatory systems to measure REM sleep have had limited success. As elevated twitching is often observed during REM sleep in some distal muscles, the aim of this study was to assess the potential for a finger-mounted device to measure finger twitches, and thereby differentiate periods of REM and non-REM (NREM) sleep.MethodsOne night of sleep data was collected by polysomnography from each of 18 (3f, 15m) healthy adults aged 23.2 ± 3.3 (mean ± SD) years. Finger movement was detected using a piezo-electric limb sensor taped to the index finger of each participant. Finger twitch densities were calculated for each stage of sleep.ResultsFinger twitch density was greater in REM than in NREM sleep (p < 0.001). Each sleep stage had a unique finger twitch density, except for REM and stage N1 sleep which were similar. Finger twitch density was greater in late REM than in early REM sleep (p = 0.005), and there was a time–state interaction: the difference between finger twitch densities in REM and NREM sleep was greater in late sleep than in early sleep (p = 0.007).ConclusionFinger twitching is more frequent in REM sleep than in NREM sleep and becomes more distinguishable as sleep progresses. Finger twitches appear to be too infrequent to make definitive 30-second epoch determinations of sleep stage. However, an algorithm informed by measures of finger twitch density has the potential to detect periods of REM sleep and provide estimates of total REM sleep time and percentage.

Surveillance During REM Sleep for the First-Night Effect.

We experience disturbed sleep in a new place, and this effect is known as the first-night effect (FNE) in sleep research. We previously demonstrated that the FNE is associated with a surveillance system in one brain hemisphere during NREM sleep, which manifests as interhemispheric asymmetry in sleep depth in the default-mode network (DMN) and increased vigilance toward monitoring external stimuli. This surveillance system may be useful for protecting vulnerable sleepers from abnormal events in unfamiliar environments. The present study investigated whether a similar surveillance system is exhibited during rapid eye movement (REM) sleep. The impacts of the FNE could be different between the phasic period, in which eyes move rapidly, and the tonic period, in which eye movement ceases, of REM sleep; without the FNE, vigilance to external stimuli is generally reduced during the phasic period but not the tonic period. Thus, REM sleep was split into phasic and tonic periods. First, we replicated previous findings showing interhemispheric asymmetry in delta activity in the DMN associated with the FNE during NREM sleep. However, during REM sleep, interhemispheric asymmetry in delta activity or theta activities, two oscillatory activities during REM sleep, was not found during the phasic or tonic periods. Next, we tested whether vigilance, as measured by evoked brain responses (P2) to deviant tones, associated with the FNE was increased in one hemisphere during REM sleep. The P2 amplitudes during the phasic period were augmented by the FNE on day 1 and were significantly larger than those on day 2 when the FNE was not present. In contrast, the P2 amplitudes during the tonic period were not different across days. The P2 amplitudes showed no interhemispheric asymmetry during the phasic or tonic periods. These results suggest that while the surveillance system exhibits interhemispheric asymmetry in sleep depth and vigilance during NREM sleep, this system shows no interhemispheric asymmetry in oscillatory activities and exhibits increased vigilance in both hemispheres only during the phasic period of REM sleep. Therefore, the surveillance system associated with the FNE may involve different mechanisms during NREM and REM sleep.

Effects of Light on Daytime Sleep in 12 Hours Night Shift Workers: A Field Study

Objectives Night shift workers suffer from sleep and daytime disturbances due to circadian misalignment. To investigate the role of environmental light in daytime sleep following 12 h-night shift work. Methods we enrolled 12 h-shift female nurses working at one university-affiliated hospital (n=10, mean age 26.6 years, shift work duration 3.8 years). This is a cross-over study to compare sleep between under light exposure (30 lux) and in the dark (<5 lux) following 12 h-night duty. Two sessions of experiments were underwent and the interval between sessions was about a month. Psychomotor vigilance test (PVT) had performed on awakening from sleep at each session and sleep-wake pattern had been monitored by actigraphy throughout the study period. Daytime sleep was also compared with night sleep of age-and gender matched daytime workers (n=10). Results Sleep parameters and PVT scores were not different between two light conditions. Activities during sleep seemed to be more abundant under 30 lux condition than in the dark, which was not significant. Compared to night sleep, daytime sleep of shift workers was different in terms of rapid eye movement (REM) sleep. Three shift workers showed sleep onset REM sleep and first REM sleep period was the longest during daytime sleep. Conclusions Unexpectedly, daytime sleep of 12 h night shift workers was well-maintained regardless of light exposure. Early occurrence of REM sleep and shorter sleep latency during daytime sleep suggest that shift workers meet with misalignment of circadian rhythm as well as increased homeostatic sleep pressure drive. Keywords: Shift work, Light exposure, Polysomnography, Sleep, Alertness

Narcolepsy - clinical spectrum, aetiopathophysiology, diagnosis and treatment.

Narcolepsy is a rare brain disorder that reflects a selective loss or dysfunction of orexin (also known ashypocretin) neurons of the lateral hypothalamus. Narcolepsy type 1 (NT1) is characterized by excessive daytime sleepiness and cataplexy, accompanied by sleep-wake symptoms, such as hallucinations, sleep paralysis and disturbed sleep. Diagnosis is based on these clinical features and supported by biomarkers: evidence of rapid eye movement sleep periods soon after sleep onset; cerebrospinal fluid orexin deficiency; and positivity for HLA-DQB1*06:02. Symptomatic treatment with stimulant and anticataplectic drugs is usually efficacious. This Review focuses onour current understanding of how genetic, environmental and immune-related factors contribute to a prominent (but not isolated) orexin signalling deficiency in patients with NT1. Data supporting the view of NT1 as a hypothalamic disorder affecting not only sleep-wake but also motor, psychiatric, emotional, cognitive, metabolic and autonomic functions are presented, along with uncertainties concerning the 'narcoleptic borderland', including narcolepsy type 2 (NT2). The limitations of current diagnostic criteria for narcolepsy are discussed, and a possible new classification system incorporating the borderland conditions is presented. Finally, advances and obstacles in the symptomatic and causal treatment of narcolepsy are reviewed.