All-night Sleep Recordings Research Articles

Regional Patterns of Elevated Alpha and High-Frequency Electroencephalographic Activity during Nonrapid Eye Movement Sleep in Chronic Insomnia: A Pilot Study.

To examine nonrapid eye movement (NREM) sleep in insomnia using high-density electroencephalography (EEG). All-night sleep recordings with 256 channel high-density EEG were analyzed for 8 insomnia subjects (5 females) and 8 sex and age-matched controls without sleep complaints. Spectral analyses were conducted using unpaired t-tests and topographical differences between groups were assessed using statistical non-parametric mapping. Five minute segments of deep NREM sleep were further analyzed using sLORETA cortical source imaging. The initial topographic analysis of all-night NREM sleep EEG revealed that insomnia subjects had more high-frequency EEG activity (> 16 Hz) compared to good sleeping controls and that the difference between groups was widespread across the scalp. In addition, the analysis also showed that there was a more circumscribed difference in theta (4-8 Hz) and alpha (8-12 Hz) power bands between groups. When deep NREM sleep (N3) was examined separately, the high-frequency difference between groups diminished, whereas the higher regional alpha activity in insomnia subjects persisted. Source imaging analysis demonstrated that sensory and sensorimotor cortical areas consistently exhibited elevated levels of alpha activity during deep NREM sleep in insomnia subjects relative to good sleeping controls. These results suggest that even during the deepest stage of sleep, sensory and sensorimotor areas in insomnia subjects may still be relatively active compared to control subjects and to the rest of the sleeping brain.

Spontaneous Swallowing during All-Night Sleep in Patients with Parkinson Disease in Comparison with Healthy Control Subjects.

Spontaneous saliva swallows (SS) appear especially during sleep. The rate of SS was rarely investigated in all-night sleep in patients with Parkinson disease (PD). Dysphagia is a frequent symptom in PD, but the rate of SS was never studied with an all-night sleep electroencephalogram (EEG). A total of 21 patients with PD and 18 age-matched healthy controls were included in the study. Frequencies of SS and coughing were studied in all-night sleep recordings of patients with PD and controls. During all-night sleep, video-EEG 12-channel recording was used including the electromyography (EMG) of the swallowing muscles, nasal airflow, and recording of vertical laryngeal movement using a pair of EEG electrodes over the thyroid cartilage. The total number of SS was increased while the mean duration of sleep was decreased in PD when compared to controls. Sialorrhea and clinical dysphagia, assessed by proper questionnaires, had no effect in any patient group. The new finding was the so-called salvo type of consecutive SS in one set of swallowing. The amount of coughing was significantly increased just after the salvo SS. In PD, the rate of SS was not sufficient to demonstrate the swallowing disorder, such as oropharyngeal dysphagia, but the salvo type of SS was quite frequent. This is a novel finding and may contribute to the understanding of swallowing problems in patients with dysphagic or nondysphagic PD.

Sleep spindles are related to schizotypal personality traits and thalamic glutamine/glutamate in healthy subjects.

Schizophrenia is a severe mental disorder affecting approximately 1% of the worldwide population. Yet, schizophrenia-like experiences (schizotypy) are very common in the healthy population, indicating a continuum between normal mental functioning and the psychosis found in schizophrenic patients. A continuum between schizotypy and schizophrenia would be supported if they share the same neurobiological origin. Two such neurobiological markers of schizophrenia are: (1) a reduction of sleep spindles (12-15 Hz oscillations during nonrapid eye movement sleep), likely reflecting deficits in thalamo-cortical circuits and (2) increased glutamine and glutamate (Glx) levels in the thalamus. Thus, this study aimed to investigate whether sleep spindles and Glx levels are related to schizotypal personality traits in healthy subjects. Twenty young male subjects underwent 2 all-night sleep electroencephalography recordings (128 electrodes). Sleep spindles were detected automatically. After those 2 nights, thalamic Glx levels were measured by magnetic resonance spectroscopy. Subjects completed a magical ideation scale to assess schizotypy. Sleep spindle density was negatively correlated with magical ideation (r = -.64, P < .01) and thalamic Glx levels (r = -.70, P < .005). No correlation was found between Glx levels in the thalamus and magical ideation (r = .12, P > .1). The common relationship of sleep spindle density with schizotypy and thalamic Glx levels indicates a neurobiological overlap between nonclinical schizotypy and schizophrenia. Thus, sleep spindle density and magical ideation may reflect the anatomy and efficiency of the thalamo-cortical system that shows pronounced impairment in patients with schizophrenia.

A transition-constrained discrete hidden Markov model for automatic sleep staging.

BackgroundApproximately one-third of the human lifespan is spent sleeping. To diagnose sleep problems, all-night polysomnographic (PSG) recordings including electroencephalograms (EEGs), electrooculograms (EOGs) and electromyograms (EMGs), are usually acquired from the patient and scored by a well-trained expert according to Rechtschaffen & Kales (R&K) rules. Visual sleep scoring is a time-consuming and subjective process. Therefore, the development of an automatic sleep scoring method is desirable.MethodThe EEG, EOG and EMG signals from twenty subjects were measured. In addition to selecting sleep characteristics based on the 1968 R&K rules, features utilized in other research were collected. Thirteen features were utilized including temporal and spectrum analyses of the EEG, EOG and EMG signals, and a total of 158 hours of sleep data were recorded. Ten subjects were used to train the Discrete Hidden Markov Model (DHMM), and the remaining ten were tested by the trained DHMM for recognition. Furthermore, the 2-fold cross validation was performed during this experiment.ResultsOverall agreement between the expert and the results presented is 85.29%. With the exception of S1, the sensitivities of each stage were more than 81%. The most accurate stage was SWS (94.9%), and the least-accurately classified stage was S1 (<34%). In the majority of cases, S1 was classified as Wake (21%), S2 (33%) or REM sleep (12%), consistent with previous studies. However, the total time of S1 in the 20 all-night sleep recordings was less than 4%.ConclusionThe results of the experiments demonstrate that the proposed method significantly enhances the recognition rate when compared with prior studies.

Nonlinear dynamical systems effects of homeopathic remedies on multiscale entropy and correlation dimension of slow wave sleep EEG in young adults with histories of coffee-induced insomnia

Investigators of homeopathy have proposed that nonlinear dynamical systems (NDS) and complex systems science offer conceptual and analytic tools for evaluating homeopathic remedy effects. Previous animal studies demonstrate that homeopathic medicines alter delta electroencephalographic (EEG) slow wave sleep. The present study extended findings of remedy-related sleep stage alterations in human subjects by testing the feasibility of using two different NDS analytic approaches to assess remedy effects on human slow wave sleep EEG. Subjects (N=54) were young adult male and female college students with a history of coffee-related insomnia who participated in a larger 4-week study of the polysomnographic effects of homeopathic medicines on home-based all-night sleep recordings. Subjects took one bedtime dose of a homeopathic remedy (Coffea cruda or Nux vomica 30c). We computed multiscale entropy (MSE) and the correlation dimension (Mekler-D2) for stages 3 and 4 slow wave sleep EEG sampled in artifact-free 2-min segments during the first two rapid-eye-movement (REM) cycles for remedy and post-remedy nights, controlling for placebo and post-placebo night effects. MSE results indicate significant, remedy-specific directional effects, especially later in the night (REM cycle 2) (CC: remedy night increases and post-remedy night decreases in MSE at multiple sites for both stages 3 and 4 in both REM cycles; NV: remedy night decreases and post-remedy night increases, mainly in stage 3 REM cycle 2 MSE). D2 analyses yielded more sporadic and inconsistent findings. Homeopathic medicines Coffea cruda and Nux vomica in 30c potencies alter short-term nonlinear dynamic parameters of slow wave sleep EEG in healthy young adults.MSE may provide a more sensitive NDS analytic method than D2 for evaluating homeopathic remedy effects on human sleep EEG patterns.

Adolescence and Parental History of Alcoholism: Insights from the Sleep EEG

Disrupted sleep is a common complaint of individuals with alcohol use disorder and in abstinent alcoholics. Furthermore, among recovering alcoholics, poor sleep predicts relapse to drinking. Whether disrupted sleep in these populations results from prolonged alcohol use or precedes the onset of drinking is not known. The aim of this study was to examine the sleep electroencephalogram (EEG) in alcohol-naïve, parental history positive (PH+), and negative (PH-) boys and girls. All-night sleep EEG recordings in 2 longitudinal cohorts (child and teen) followed at 1.5 to 3 year intervals were analyzed. The child and teen participants were 9/10 and 15/16 years old at the initial assessment, respectively. Parental history status was classified by Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria applied to structured interviews (DIS-IV) resulting in 14 PH- and 10 PH+ children and 14 PH- and 10 PH+ teens. Sleep data were visually scored in 30-second epochs using standard criteria. Power spectra were calculated for EEG derivations C3/A2, C4/A1, O2/A1, O1/A2 for nonrapid eye movement (NREM) and rapid eye movement (REM) sleep. We found no difference between PH+ and PH- individuals in either cohort for any visually scored sleep stage variable. Spectral power declined in both cohorts across assessments for NREM and REM sleep in all derivations and across frequencies independent of parental history status. With regard to parental history, NREM sleep EEG power was lower for the delta band in PH+ teens at both assessments for the central derivations. Furthermore, power in the sigma band for the right occipital derivation in both NREM and REM sleep was lower in PH+ children only at the initial assessment. We found no gross signs of sleep disruption as a function of parental history. Modest differences in spectral EEG power between PH+ and PH- children and teens indicate that a marker of parental alcohol history may be detectable in teens at risk for problem drinking.

Developmental changes in brain connectivity assessed using the sleep EEG

Adolescence represents a time of significant cortical restructuring. Current theories posit that during this period connections between frequently utilized neural networks are strengthened while underutilized synaptic connections are discarded. The aim of the present study was to examine the developmental evolution of connectivity between brain regions using the sleep EEG. All-night sleep EEG recordings in two longitudinal cohorts (children and teens) followed at 1.5–3 year intervals and one cross-sectional cohort (adults) were analyzed. The children and teen cohorts were 9/10 and 15/16 years at the initial assessment; ages of the adults were 20 to 23 years. Intrahemispheric, interhemispheric, and diagonal coherence was measured between all six possible pairings of two central (C3/A2 and C4/A1) and two occipital (O2/A1 and O1/A2) derivations during slow wave, stage 2, and, REM sleep. Within-subjects analyses were performed for the children and teen cohorts, and a linear regression analysis was performed across every assessment of all cohorts. Within-subject analyses revealed a maturational increase in coherence for both age cohorts, though the frequencies, sleep states, and regions differed between cohorts. Regression analysis across all age cohorts showed an overall linear increase in left and right intrahemispheric coherence for all sleep states across frequencies. Furthermore, coherence between diagonal electrode pairs also increased in a linear manner for stage 2 and REM sleep. No age-related trend was found in interhemispheric coherence. Our results indicate that sleep EEG coherence increases with age and that these increases are confined to specific brain regions. This analysis highlights the utility of the sleep EEG to measure developmental changes in brain maturation.

Primary open angle glaucoma and snoring: Prevalence of OSAS

Obstructive sleep apnea syndrome (OSAS) may be suspected at interview, notably in case of snoring. Various studies suggested a link between primary open angle glaucoma (POAG) and OSAS. The present study sought to determine OSAS prevalence in POAG associated with snoring. Thirty-one snoring glaucomatous patients prospectively underwent simplified polysomnography. Ophthalmologic examination ruled out secondary glaucoma and assessed the glaucomatous neuropathy. 49% of the patients included were diagnosed with OSAS. Ophthalmologically, glaucoma showed no specific characteristics. Given the high-prevalence of OSAS in patients with POAG, presence of snoring should be explored at interview. Conversely, patients who snore should be asked whether they have POAG, and if so, should undergo all-night sleep recording to explore for OSAS.

Effects of homeopathic medicines on polysomnographic sleep of young adults with histories of coffee-related insomnia

Background Homeopathy, a common form of alternative medicine worldwide, relies on subjective patient reports for diagnosis and treatment. Polysomnography offers a modern methodology for evaluating the objective effects of taking homeopathic remedies that clinicians claim exert effects on sleep quality in susceptible individuals. Animal studies have previously shown changes in non rapid eye movement sleep with certain homeopathic remedies. Methods Young adults of both sexes (ages 18–31) with above-average scores on standardized personality scales for either cynical hostility or anxiety sensitivity (but not both) and a history of coffee-induced insomnia participated in the month-long study. At-home polysomnographic recordings were obtained on successive pairs of nights once per week for a total of eight recordings (nights 1, 2, 8, 9, 15, 16, 22, 23). Subjects ( N = 54) received placebo pellets on night 8 (single-blind) and verum pellets on night 22 (double-blind) in 30c doses of one of two homeopathic remedies, Nux Vomica or Coffea Cruda. Subjects completed daily morning sleep diaries and weekly Pittsburgh sleep quality index scales, as well as profile of mood states scales at bedtime on polysomnography nights. Results Verum remedies significantly increased PSG total sleep time and NREM, as well as awakenings and stage changes. Changes in actigraphic and self-rated scale effects were not significant. Conclusions The study demonstrated the feasibility of using in-home, all-night sleep recordings to study homeopathic remedy effects. Findings are similar though not identical to those reported in animals with the same remedies. Possible mechanisms include initial disruption of the nonlinear dynamics of sleep patterns by the verum remedies.

Automated Sleep-Spindle Detection in Healthy Children Polysomnograms

We present a new methodology to detect and characterize sleep spindles (SSs), based on the nonlinear algorithms, empirical-mode decomposition, and Hilbert-Huang transform, which provide adequate temporal and frequency resolutions in the electroencephalographic analysis. In addition, the application of fuzzy logic allows to emulate expert's procedures. Additionally, we built a database of 56 all-night polysomnographic recordings from children for training and testing, which is among the largest annotated databases published on the subject. The database was split into training (27 recordings), validation (10 recordings), and testing (19 recordings) datasets. The SS events were marked by sleep experts using visual inspection, and these marks were used as golden standard. The overall SS detection performance on the testing dataset of continuous all-night sleep recordings was 88.2% sensitivity, 89.7% specificity, and 11.9% false-positive (FP) rate. Considering only non-REM sleep stage 2, the results showed 92.2% sensitivity, 90.1% specificity, and 8.9% FP rate. In general, our system presents enhanced results when compared with most systems found in the literature, thus improving SS detection precision significantly without the need of hypnogram information.

Systematic performance evaluation of a continuous-scale sleep depth measure

In this article, systematic performance evaluation of a continuous-scale sleep depth measure will be discussed. Our main objective has been to select the adjustable analysis parameters such that the best possible correspondence between method output and standard visual sleep staging could be achieved. Sleep depth estimation was based on continuous monitoring of short-time EEG synchronization through the local mean frequency of the EEG. During the experiments, total amount of 752 different combinations of four adjustable parameters were compared based on all-night sleep EEG recordings of 15 healthy subjects. Optimization strategy applied was based on maximizing the weighted average of pair-wise separabilities of EEG mean frequency distributions in all the standard sleep stage pairs. Finally, robustness of the optimized parameters was verified with an independent dataset of 34 all-night sleep recordings. Our results show that clear topological differences between brain hemispheres and different electrode locations exist. Performance improvements of even 20–30% units can be achieved by proper selection of analysis parameters and the EEG derivation used for the analysis. Remarkable independence of system performance on the analysis window length leads to improved temporal resolution compared to that achieved through standard visual analysis. In addition to giving practical suggestions on the parameter selection, we also propose a possible method for improving stage separability especially between S2 and REM.

Apnea patients show a frontopolar inter-hemispheric spindle frequency difference

Sleep apnea syndrome is known to disturb sleep. The purpose of the present work was to study spindle frequency in apnea patients. All-night sleep EEG recordings of 15 apnea patients and 15 control subjects with median ages of 47 and 46 years, respectively, were studied. A previously presented and validated multi-channel spindle analysis method was applied for automatic detection and frequency analysis of bilateral frontopolar and central spindles. Bilateral frontopolar spindles of apnea patients were found to show lower frequencies on the left hemisphere than on the right. Such an inter-hemispheric spindle frequency difference in apnea patients is a novel finding. It could be that the hypoxias and hypercapnias caused by apneic episodes result in local disruption in the regulation of sleep in the frontal lobes.

To sleep, perchance to speak

Few disorders provoke such intense anxiety and fear among parents as does isolated language regression and language regression with autistic regression among young children. The possible increase in prevalence of autism in the United States1 has helped focus attention on our inability to treat or prevent autism.2 Case series describing improved language function after treatment of Landau-Kleffner syndrome (LKS) and electrographic status epilepticus in sleep (ESES)3,4 have been a source of hope for parents of children with language regression and normal hearing, but no treatment has been proven effective in improving language function. Child neurologists and developmental pediatricians often perform all-night sleep recordings on children with language regression hoping to find this devastating, yet theoretically treatable, condition. Experts have debated whether these language regression disorders represent a spectrum of phenotypes with common features that allow them to be grouped together for clinical studies, or whether they are distinct phenotypic syndromes that should be considered separately.5,6 In this issue of Neurology, …

A Case Report of Zolpidem-Induced Somnambulism.

Sir: The physiology of sleep, memory, awareness, and arousal can be influenced by different drugs.1 Zolpidem tartrate is a nonbenzodiazepine hypnotic agent of the imid-azopyridine group with a rapid onset and short duration of action. Its side effect profile is milder than those of benzodiazepines and barbiturates used for treating insomnia.2 To our knowledge, there are 5 published articles3–7 related to zolpidem-induced somnambulism. Somnambulism, or sleepwalking, could be dangerous due to the possibility of accidental injury. Here, we present a case of somnambulism associated with zolpidem use. Case report. Mr. A, a 19-year-old white man, had a history of and current diagnoses of DSM-IV schizoaffective disorder and impulse-control disorder. The patient lived with his parents and a younger brother. He worked as a volunteer at a university hospital and had received a general equivalency diploma. Mr. A had no current or past history of substance abuse and did not smoke or drink alcohol. His medical history was unremarkable. The patient had a history of 2 psychiatric hospitalizations for worsening of his symptoms. He had no personal or family history of sleepwalking. In the past, olanzapine and paroxetine had been tried without successful results. Mr. A was stable on his medications, which included aripiprazole 15 mg once per day, venlafaxine extended release 150 mg once per day, and quetiapine 50 mg once per day. He received no other medications, including herbal supplements. During the course of his treatment, Mr. A began complaining of insomnia, for which brief zolpidem treatment was prescribed. He was started on treatment with zolpidem 10 mg orally at bedtime on an as-needed basis for insomnia. Within a few days of the initiation of zolpidem treatment, the patient's family noticed the patient waking up in the middle of night and walking into their room with a staring expression and some incoherent speech. The patient had no memory of this event in the morning. This sleepwalking episode was attributed to zolpidem, as no medication change was made besides initiating zolpidem and the patient had no history of such episodes in the past. Zolpidem treatment was stopped, and since then, no complaints of sleepwalking have been reported. Somnambulism, or sleepwalking, generally occurs during stages 3 and 4 of slow-wave sleep.8 During an episode of somnambulism, the normal arousal mechanism is altered, which results in partial arousal without full consciousness.9 Electroencephalographic changes associated with the use of zolpidem include suppression of REM sleep.10 It has been suggested that some drugs produce a physiologic state during slow-wave sleep that can present clinically as somnambulism.8 A definitive diagnosis of somnambulism usually requires all-night sleep recordings,8 which were not performed on our patient. We suggest that when seeking an etiology of somnambulism in a patient, a careful review of the patient's current medications should be performed.

Epilepsia y ciclo sueño-vigilia

Sleep and epilepsy have strong reciprocal influences and this is true for all kinds of epilepsies. The interictal paroxysmal activity increases in slow wave sleep and the localization of the primary epileptogenic area is more reliable in paradoxical sleep.From a practical point of view, an all-night sleep recording or a short-term sleep EEG recording during daytime, preceded or not by sleep deprivation, are both convenient procedures for the diagnosis and for evaluating the prognosis of epilepsy. Aldrich et al have reported the usefulness of video-EEG polysomnography in the diagnosis of nocturnal seizures versus non-epileptic manifestations such NREM/REM dyssomnias, even in patients with no known history of epilepsy. Sleepiness and nocturnal sleep disturbances have long been recognized in epileptic patients. A review of the literature shows a high incidence of sleep complaints among epileptics. The interaction of epilepsy, antiepileptic drugs and the sleep-wake cycle has been extensively investigated.

The time course of high-frequency bands (15–45 Hz) in all-night spectral analysis of sleep EEG

Objective: The EEG spectral content of all-night sleep recordings obtained in 7 healthy young subjects, aged 18–20 years, including frequencies up to 45 Hz, was studied in order to detect eventual changes in the high-frequency range similar to those reported by magnetic field recording during REM sleep at 40 Hz. Methods: For this purpose, power spectra were calculated with a fast Fourier transform and the power of the bands ranging 0.75–4.50 Hz (Delta), 4.75–7.75 (Theta), 8.00–12.25 (Alpha), 12.50–15.00 (Sigma), 15.25–24.75 (Beta), 25.00–34.75 (Gamma1), and 35.00–44.75 (Gamma 2) was calculated for-the whole period of analysis (7 h). Also two additional time series: the ratio between Beta and Gamma2, and between Gamma1 and Gamma2 were calculated (Beta and Gamma ratios). Results: Beta and Gamma1 showed small changes with a tendency to increase during REM sleep; Gamma2, on the contrary, showed small changes with a tendency to decrease during REM sleep. Beta and Gamma ratio peaks were clearly correlated with the occurrence of REM sleep. The small changes shown by Beta, Gamma1 and Gamma2 were not statistically significant; on the contrary, Beta ratio and Gamma ratio showed the most important statistical significance values being highest during REM sleep and lowest during slow-wave sleep. Finally, the calculation of the linear correlation coefficient and of the cross-correlation between the different bands showed a clear reciprocity between Delta and Beta and Gamma ratios. Conclusions: Our study shows a new method for the analysis of high frequencies (up to 45 Hz) in the scalp-recorded sleep EEG which allowed us to better define, as compared to previous studies on the same topic, the changes in power characteristically associated with REM sleep and correlated with the REM/non-REM ultradian rhythm, and to propose it as a tool for future studies.

Low-frequency (

Low-frequency (<1 Hz) oscillations in intracellular recordings from cortical neurons were first reported in the anaesthetized cat and then also during natural sleep. The slow sequences of hyperpolarization and depolarization were reflected by slow oscillations in the electroencephalogram. The aim of the present study was to examine whether comparable low-frequency components are present in the human sleep electroencephalogram. All-night sleep recordings from eight healthy young men were subjected to spectral analysis in which the low-frequency attenuation of the amplifier was compensated. During sleep stages with a predominance of slow waves and in the first two episodes of non-rapid-eye-movement sleep, the mean power spectrum showed a peak at 0.7–0.8 Hz (range 0.55–0.95 Hz). The typical decline in delta activity from the first to the second non-rapid-eye-movement sleep episode was not present at frequencies below 2 Hz. To detect very low frequency components in the pattern of slow waves and sleep spindles, a new time series was computed from the mean voltage of successive 0.5 s epochs of the low-pass (<4.5 Hz) or band-pass (12–15 Hz) filtered electroencephalogram. Spectral analysis revealed a periodicity of 20–30 s in the prevalence of slow waves and a periodicity of 4 s in the occurrence of activity in the spindle frequency range. The results demonstrate that distinct components below 1 Hz are also present in the human sleep electroencephalogram spectrum. The differences in the dynamics between the component with a mean peak value at 0.7–0.8 Hz and delta waves above 2 Hz is in accordance with results from animal experiments.

Time-dependent sensitization of plasma beta-endorphin in community elderly with self-reported environmental chemical odor intolerance

This study examined plasma beta-endorphin as a marker of the physiological stress response in community elderly who were either high (n = 15) or low (n = 15) in self-rated frequency of illness from environmental chemical odors. Individuals who report nonatopic multiple sensitivities to or intolerances for low levels of environmental chemicals also claim high rates of comorbid food sensitivities or intolerances. Subjects gave 9 AM blood samples for plasma beta-endorphin 90 min after ingesting either 1% fat cow's milk or a soy-based nondairy drink, on six different mornings in the laboratory after all-night sleep recordings. The six sessions-were divided into three sets of two successive days each, with each set [involving baseline (ad lib milk), nondairy (soy-based), and dairy diets] separated from the next by 3 weeks. In the chemically tolerant subjects, stably lower beta-endorphin levels suggested that milk may have been a physiologically less stressful beverage than was the soy drink. In contrast, the chemical odor intolerant group exhibited a) increased levels of plasma beta-endorphin averaged over the 6 days (p = .02); and b) marked fluctuations in endorphin from one laboratory day to the next (Group x Diet x Day interaction, p = .005). The findings were consistent with time-dependent, context-dependent sensitization of beta-endorphin in the chemical odor intolerant individuals.

The sleep of non-depressed patients with panic disorder: a comparison with normal controls.

All-night sleep EEG recordings were performed in non-depressed patients with panic disorder, agoraphobia, and a group of age- and sex-matched normal controls. Patients were selected according to DSM-IV and all subjects were studied under drug-free conditions. In addition to sleep continuity disturbances, patients with panic disorder have a reduced percentage of slow wave sleep, mainly due to diminished amounts of stage 4. REM sleep characteristics are identical in the two groups. When depressive co-morbidity and non-specific causes of insomnia are excluded, the sleep EEG of panic patients seems to be characterized by modest changes in sleep continuity and sleep architecture. These findings favour the existence of a neurophysiological frontier between anxiety disorders and depressive illness.

Shifts and awakenings: Valuable indicators of the quality of sleep: Do these parameters react differently to hypnotics?

In order to test the assumption that the sleep stability increases as the number of shifts and awakenings decreases, all-night sleep recordings (registered at home) were reanalyzed. The registrations belong to 10 young good sleepers, 10 adult good sleepers, 10 insomnia patients without treatment, 10 treated with a benzodiazepine and 10 treated with a nonbenzodiazepine hypnotic, 10 patients with proven narcolepsy, and 10 with obstructive sleep apnea syndrome (OSAS). For each of the categories NREM-1–2, NREM 3–4, and REM sleep, indices were defined as the number of shifts and awakenings that occurred per hour. Our results show that the indices of awakenings for the good as well for the bad sleepers were similar, whereas the indices of awakenings were very group dependent. We interpreted these results as showing that awakenings are valuable indicators for studying the quality of sleep, whereas shifts are not.