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Background: It is well-established that environmental noise can disrupt sleep, and cause a mismatch between subjective and objective sleep, which is known as "sleep misperception". Naturalistic studies indicate that pre-sleep cognitive arousal and sleep misperception are associated in the context of noise. However, it is not known if this is the case when ecologically valid noises are specifically played during non-rapid eye movement (NREM) sleep, which is susceptible to noise-related disruption. The present study evaluated if pre-sleep cognitive arousal was associated with sleep misperception in healthy normal sleepers, when unexpected ecologically valid common nocturnal noises were played during NREM sleep. Methods: Eighteen healthy sleepers (Mage = 23.37 years, SDage = 3.21 years) participated. Sleep was measured objectively on three consecutive nights using polysomnography, in a sleep laboratory environment, and subjectively, through participant estimates of total sleep time (TST). Night 1 was a baseline night where no noises were played. On Night 2, noises, which were chosen to be representative of habitual nocturnal noises heard in home environments, were played to participants via in-ear headphones after 5 min of objective sleep. Results: Unexpectedly, habitual pre-sleep cognitive arousal was not associated with subjective–objective TST discrepancy on Night 2. Conclusions: These results suggest that in healthy sleepers, when ecologically valid noises are played unexpectedly during NREM sleep in an unfamiliar sleep laboratory environment the subjective experience of sleep is not associated with pre-sleep cognitive arousal, or negatively impacted by noise exposure. [ABSTRACT FROM AUTHOR]

Nightmares are often associated with psychiatric disorders and acute stress. This study explores how the COVID‐19 pandemic may have influenced the content of nightmares. A sample of N = 419 US adults completed online surveys about sleep and COVID‐19 experiences. Participants were asked about the degree to which they agreed with statements linking greater general stress, worse overall sleep and more middle‐of‐the‐night insomnia with the COVID‐19 pandemic. They were also asked if, during the pandemic, they experienced nightmares related to various themes. Logistic regression analyses examined each nightmare content as outcome and increased stress, worse sleep and more middle‐of‐the‐night insomnia as predictors, adjusted for age, sex and race/ethnicity. Those who reported greater general COVID‐related stress were more likely to have nightmares about confinement, failure, helplessness, anxiety, war, separation, totalitarianism, sickness, death, COVID and an apocalypse. Those who reported worsened sleep were more likely to have nightmares about confinement, oppression, failure, helplessness, disaster, anxiety, evil forces, war, domestic abuse, separation, totalitarianism, sickness, death, COVID and an apocalypse. Those who reported worsened middle‐of‐the‐night insomnia were more likely to have nightmares about confinement, oppression, failure, helplessness, disaster, anxiety, war, domestic abuse, separation, totalitarianism, sickness, death, COVID and an apocalypse. These results suggest that increased pandemic‐related stress may induce negatively‐toned dreams of specific themes. Future investigation might determine whether (and when) this symptom indicates an emotion regulation mechanism at play, or the failure of such a mechanism. [ABSTRACT FROM AUTHOR]

Emotional reactivity in insomnia is affected both subjectively and on a physiological level for negative emotional material, but little is known about reactions to positive stimuli. We here investigated whether in younger adult insomnia patients, presentation of short humorous films would lead to heart rate decreases during and after film viewing, as compared to heart rate changes when falling asleep. Investigating 20 participants with DSM‐5‐diagnosed insomnia and 18 participants without insomnia, we found that heart rate decreased when falling asleep, increased when watching humorous films and returned to normal values afterwards for all participants. Film‐related heart rate increases were strongly related to humour ratings of the films. No differences were found between those with and without insomnia on subjective ratings of the films, film‐related heart rate changes or when falling asleep. We conclude that the experience of positive daily life stimuli in younger adults is not affected by insomnia in our study, despite insomnia having a known more profound effect on negative stimuli. Future studies exploring insomnia‐related autonomous nervous system responses combining different neurophysiological modalities should confirm our findings. [ABSTRACT FROM AUTHOR]

Objective: The objective of the present study was to evaluate the relationship between objective and subjective sleep quality and objective and subjective evaluation of cognitive performance in older adults suffering of chronic insomnia (using or not benzodiazepines, BZs) or self-reported good sleepers.Methods: Three groups of participants 55 years and older were evaluated: 20 insomnia sufferers using BZs chronically, 20 drug-free insomnia sufferers and 20 good sleepers. Objective sleep (PSG) and subjective sleep (sleep diaries, SD) were measured. Objective measures of cognitive performance (attention/concentration, verbal/visual memory, executive function and psychomotor speed) and subjective perception of daily performance were evaluated.Results: Correlational analysis revealed that objective and subjective measures of daytime performance are differentially related to sleep quality for the three groups. An objective good night of sleep is associated with better cognitive performance in good sleepers and drug-free individuals. On the other hand, the impression of having slept well is related to better cognitive performance in good sleepers and chronic insomnia sufferers using BZs.Conclusion: Daytime performance and sleep quality are related, but differently so for a good sleeper, an insomnia sufferer without treatment, or one using BZs to alleviate sleep difficulties. [ABSTRACT FROM AUTHOR]

Insomnia sufferers (INS) are cortically hyperaroused during sleep, which seems to translate into altered information processing during nighttime. While information processing, as measured by event-related potentials (ERPs), during wake appears to be associated with sleep quality of the preceding night, the existence of such an association during nighttime has never been investigated. This study aims to investigate nighttime information processing among good sleepers (GS) and INS while considering concomitant sleep quality. Following a multistep clinical evaluation, INS and GS participants underwent 4 consecutive nights of PSG recordings in the sleep laboratory. Thirty nine GS (mean age 34.56 ± 9.02) and twenty nine INS (mean age 43.03 ± 9.12) were included in the study. ERPs (N1, P2, N350) were recorded all night on Night 4 (oddball paradigm) during NREM sleep. Regardless of sleep quality, INS presented a larger N350 amplitude during SWS ( p = 0.042) while GS showed a larger N350 amplitude during late-night stage 2 sleep ( p = 0.004). Regardless of diagnosis, those who slept objectively well showed a smaller N350 amplitude ( p = 0.020) while those who slept subjectively well showed a smaller P2 ( p < 0.001) and N350 amplitude ( p = 0.006). Also, those who reported an objectively bad night as good showed smaller P2 ( p < 0.001) and N350 ( p = 0.010) amplitudes. Information processing seems to be associated with concomitant subjective and objective sleep quality for both GS and INS. However, INS show an alteration in information processing during sleep, especially for inhibition processes, regardless of their sleep quality. [ABSTRACT FROM AUTHOR]

Insomnia is a symptom, a syndrome and a comorbid disorder. Its diagnosis relies on subjective reports from the afflicted individual and is defined as difficulties in initiating sleep, maintaining sleep, waking up too early or non-restorative sleep. However, insomnia and especially, primary insomnia, has received much attention in insomnia research with the use of objective measures. Insomnia, its peculiarities, most frequent subtypes and two most prominent models will first be briefly introduced. Then, insomnia will be reviewed according to results obtained with the use of neurophysiological measures as basic/traditional as polysomnography to more sophisticated ones such as power spectral analysis, neuroimaging, cyclic alternating patterns and event-related potentials. In addition, a review of the discrepancies between subjective and objective reports of cognitive alterations through neuropsychological testing is offered. The need to combine measures is then highlighted in conclusion. [ABSTRACT FROM AUTHOR]

Abstract: Methylmercury (MeHg) and polychlorinated biphenyls (PCBs) are seafood contaminants known for their adverse effects on neurodevelopment. This study examines the relation of developmental exposure to these contaminants to information processing assessed with event-related potentials (ERPs) in school-aged Inuit children from Nunavik (Arctic Québec). In a prospective longitudinal study on child development, exposure to contaminants was measured at birth and 11 years of age. An auditory oddball protocol was administered at 11 years to measure ERP components N1 and P3b. Multiple regression analyses were performed to examine the associations of levels of the contaminants to auditory oddball performance (mean reaction time, omission errors and false alarms) and ERP parameters (latency and amplitude) after control for potential confounding variables. A total of 118 children provided useable ERP data. Prenatal MeHg exposure was associated with slower reaction times and fewer false alarms during the oddball task. Analyses of the ERP parameters revealed that prenatal MeHg exposure was related to greater amplitude and delayed latency of the N1 wave in the target condition but not to the P3b component. MeHg effects on the N1 were stronger after control for seafood nutrients. Prenatal PCB exposure was not related to any endpoint for sample as a whole but was associated with a decrease in P3b amplitude in the subgroup of children who had been breast-fed for less than 3 months. Body burdens of MeHg and PCBs at 11 years were not related to any of the behavioural or ERP measures. These data suggest that prenatal MeHg exposure alters attentional mechanisms modulating early processing of sensory information. By contrast, prenatal PCB exposure appears to affect information processing at later stages, when the information is being consciously evaluated. These effects seem to be mitigated in children who are breast-fed for a more extended period. [Copyright &y& Elsevier]

Abstract: Objective: Spontaneous K-complexes are electroencephalographic features unique to non-rapid eye movement sleep. It has been suggested that this phasic event is a sleep-protective mechanism. Because insomnia sufferers report poor sleep quantity and quality, the objective of this study was to document the occurrence of spontaneous K-complexes in Stage 2 sleep of individuals with chronic insomnia. Specifically, the number and density of spontaneous K-complexes were studied in psychophysiological insomnia sufferers. Setting: This study took place in a sleep and event-related potentials laboratory. Design: Spontaneous K-complexes were scored during Stage 2 sleep on the second and third nights of a four-consecutive-nights protocol of polysomnographic recordings. Participants: The sample included 14 participants suffering from psychophysiological insomnia (INS group; mean age=44.1 years) and 14 good sleepers (mean age=38.1 years). Participants underwent sleep and psychological evaluations. INS group participants met the diagnostic criteria for primary psychophysiological insomnia (mean duration of insomnia=9.6 years). Intervention: Not applicable. Results: The total number of spontaneous K-complexes and the density according to the total time spent in Stage 2 sleep (spontaneous K-complexes per minute) were compiled. Repeated-measures analyses of variance showed no significant difference in the number and density of spontaneous K-complexes between the INS group (313.98 and 2.66) and the GS group (361.10 and 2.88), respectively. Conclusion: These results suggest no deficiency in the sleep-protective mechanism of psychophysiological insomnia sufferers in comparison with good sleepers, as measured by the spontaneous K-complexes'' number and density. [Copyright &y& Elsevier]

Abstract: Introduction: Our recent ERPs study suggested inhibition deficits in addition to cortical arousal in insomnia sufferers (INS) relative to good sleepers (GS). The aim of the present study was to investigate the relation between objective sleep parameters and the amplitudes and latencies of ERPs components N1 and P2 in a multi-assessment protocol. Methods: Participants, 15 INS and 16 GS, underwent four consecutive nights of polysomnography recordings (N1 to N4). ERPs in the evening and upon awakening were recorded on N3 and N4, with the addition of sleep-onset recordings on N4. Auditory stimuli consisted of ‘standard’ and ‘deviant’ tones. Objective sleep measures were computed on each night [sleep efficiency (SE), wake after sleep onset (WASO), total sleep time (TST) and sleep-onset latency (SOL)]. The amplitude and latency of N1 and P2 components were assessed for each recorded session on each night and related to measures of sleep of the same nights (N3 and N4). Results: Pearson''s correlations between the amplitude and latency of N1 and P2 and objective sleep measures revealed that arousal levels in the evening, before going to bed seem to have an impact on subsequent sleep quality. Furthermore, the sleep quality of the previous night also appeared to have an impact on morning (daily) arousal levels. Conclusion: These results suggest that hyperactivation and inhibition deficits present in insomnia sufferers are directly associated with a poorer sleep quality. This highlights once again that when information processing and/or performance is assessed, the sleep quality of the night preceding the evaluation shall be documented. [Copyright &y& Elsevier]

Abstract: Objective: A sleep spindle is an electroencephalographic feature that is unique to sleep. It has been suggested that this phasic event has a sleep-protective function. The objective of the present study was to document one aspect of sleep protection in chronic insomnia sufferers: the number and density of sleep spindles in Stage 2 sleep. Methods: Sleep spindles were scored during Stage 2 sleep on the second and third nights of a protocol of polysomnographic recordings that lasted for four consecutive nights. The sample included 16 participants suffering from insomnia (INS group; mean age=43.4 years) and 14 good sleepers (GS group; mean age=38.1 years). Participants underwent sleep and psychological evaluations. The INS group participants met the diagnostic criteria for primary psychophysiological insomnia (mean duration of insomnia=9.6 years). Results: The total number of sleep spindles in Stage 2 sleep and the density (sleep spindles per minute) according to the total time spent in Stage 2 sleep were compiled. Repeated-measures analyses of variance showed no significant difference in the number and in the density of sleep spindles between the INS group (68.46 and 0.60, respectively) and the GS group (56.28 and 0.46, respectively). Conclusion: These results suggest no deficiency in the sleep-protection mechanism of psychophysiological insomnia sufferers in comparison with good sleeper controls, as measured by the number and density of sleep spindles. [Copyright &y& Elsevier]

Forty-five adults with primary insomnia received cognitive-behavioral therapy (CBT) implemented in a group therapy format, in individual face-to-face therapy or through brief individual telephone consultations. The results indicate that CBT was effective in improving sleep parameters with all 3 methods of treatment implementation, and there was no significant difference across methods of implementation. All 3 treatment modalities produced improvements in sleep that were maintained for 6 months after treatment completion. These results suggest that group therapy and telephone consultations represent cost-effective alternatives to individual therapy for the management of insomnia. [ABSTRACT FROM AUTHOR]

Following the loss of wakeful consciousness, the averaging of responses to stimuli produce evoked potential waveforms with prominent components either unique to or greatly enhanced by non-REM sleep. In the sleep onset periods (stage 1) these are the P2 and N350. Following the establishment of stable sleep (stage 2 and SWS), the N550 and P900 are also prominent. Investigation of the EEG associated with individual responses indicates that a good proportion of stimuli elicit, K-complexes or vertex sharp waves (VSWs) and occasionally will elicit both. Recent work has indicated that the N550 in the averaged response is due to the presence of K-complexes and that the N350 is at least largely due to the presence of VSWs. The large size of these grapho-elements indicates that they are probably produced by a synchronized discharge of multiple neural units. Both are readily observed in the absence of external stimulation and occur as normal components of sleep, indeed the K-complex is used as one of the identifying features of the onset of stable non-REM sleep. The present review details the investigation of these features and their associated evoked potential components, in terms of stimulus features, brain states associated with their production, their scalp topography, and changes as a function of age. [Copyright &y& Elsevier]

This study evaluated the familial incidence of sleep disturbances among individuals with insomnia complaints. The sample consisted of 285 patients evaluated for insomnia at a sleep disorders clinic. All patients completed a sleep survey and underwent a semistructured clinical interview as part of their initial evaluation of insomnia. Information on the presence and nature of sleep disturbances among their family members (first- and second-degree relatives) was obtained from a sleep survey. The findings indicate that 35% of patients consulting for insomnia had a positive family history of sleep disturbances. Insomnia was the most common type of sleep disturbance identified (76%) and the mother was the most frequently afflicted family member. Reports of sleep disturbances among a family member were more prevalent when the onset of insomnia was before 40-years-old than when it was later in life. A positive family history was slightly higher when the insomnia complaint involved sleep-onset difficulties relative to sleep-maintenance or mixed insomnias. Although the present findings suggest that a positive family history of insomnia may be a potential risk factor for insomnia, it is unclear whether this reflects a genetic predisposition or a social learning phenomenon. [ABSTRACT FROM AUTHOR]

Summary: Stimulus control is part of the widely used cognitive behavioural therapy for insomnia. However, there is a lack of knowledge about its mechanisms of action and effectiveness when used alone. This systematic review with network meta‐analysis aimed to evaluate stimulus control efficacy when used alone compared with cognitive behavioural therapy for insomnia or its components. The review also documented stimulus control mechanisms of action proposed by the authors. A search was conducted in several bibliographic databases (MEDLINE, PsycINFO, Embase, CINAHL, Psychology Behavioural Sciences Collection, Web of Science, and Cochrane Library) and in two registers from 1972 to June 2022. Randomised studies with adult participants presenting a diagnosis of insomnia and including at least one stimulus control instruction in a treatment group were included. Risk of bias was assessed with the Quality Assessment of Controlled Intervention Studies. Twenty‐three studies were included and three network meta‐analyses were conducted. The quality of included studies was generally poor. Results indicate that stimulus control is an effective intervention to improve insomnia compared with control conditions. Not all stimulus control instructions seem essential, especially those known to recondition the bedroom for sleep. The review challenges the classical conditioning hypothesis. Results should be interpreted cautiously given the small number of studies included, bias risk, and inconsistencies in the network meta‐analysis. Rigorous research is needed in evaluating stimulus control efficacy and mechanisms. [ABSTRACT FROM AUTHOR]

Specific noises (e.g., traffic or wind turbines) can disrupt sleep and potentially cause a mismatch between subjective sleep and objective sleep (i.e., "sleep misperception"). Some individuals are likely to be more vulnerable than others to noise-related sleep disturbances, potentially as a result of increased pre-sleep cognitive arousal. The aim of the present study was to examine the relationships between pre-sleep cognitive arousal and sleep misperception. Sixteen healthy sleepers participated in this naturalistic, observational study. Three nights of sleep were measured using actigraphy, and each 15-s epoch was classified as sleep or wake. Bedside noise was recorded, and each 15-s segment was classified as containing noise or no noise and matched to actigraphy. Participants completed measures of habitual pre-sleep cognitive and somatic arousal and noise sensitivity. Pre-sleep cognitive and somatic arousal levels were negatively associated with subjective–objective total sleep time discrepancy (p < 0.01). There was an association between sleep/wake and noise presence/absence in the first and last 90 min of sleep (p < 0.001). These results indicate that higher levels of habitual pre-sleep arousal are associated with a greater degree of sleep misperception, and even in healthy sleepers, objective sleep is vulnerable to habitual bedside noise. [ABSTRACT FROM AUTHOR]

Summary The present study evaluates the efficacy of behavioural therapy adapted for shift work disorder with a randomised control design in a healthcare population. Forty‐three night shift workers (m. age: 34 years; 77% women) experiencing shift work disorder were randomised to either the behavioural therapy for shift work disorder (BT‐SWD) or a waiting‐list control group offered after the waiting period. Participants completed questionnaires on insomnia, sleepiness and mental health pre‐ and post‐treatment, pre‐ and post‐waiting, and at follow‐up, and a sleep diary. As night shift workers alternate between sleeping during the day after their night shifts and transitioning to nighttime sleep on days off, insomnia severity and sleep variables were analysed for daytime and nighttime sleep. The BT‐SWD involved sleep restriction therapy, stimulus control and fixed sleep periods in the dark. Statistical analyses were performed under intent‐to‐treat and per‐protocol approaches. Repeated‐measures two‐way ANCOVA analysis, controlling for age, sex and pre‐treatment daytime total sleep time, was performed with Bonferroni corrections, and between‐group effect sizes computed. Fourteen participants dropped out after randomisation. Under the intent‐to‐treat analysis, BT‐SWD participants had a significant greater decrease in daytime insomnia severity and an increase in daytime total sleep time at post‐treatment than the control group, with large between‐group effect sizes (−1.25 and 0.89). These corresponding results were also significant with large effect sizes under the per‐protocol analysis. Sleepiness, anxiety and depression levels improved at post‐treatment and maintained at follow‐up when the BT‐SWD treated controls were added to the BT‐SWD group. The behavioural therapy for shift work disorder can be used to improve the sleep and mental health of healthcare night workers. [ABSTRACT FROM AUTHOR]

Cortical hyperarousal is higher in insomnia sufferers (INS) than in good sleepers (GS) and could be related to an alteration in sleep protection mechanisms, like reduced density or altered characteristics in sleep spindles. The deficient sleep protection mechanisms might in turn enhance underestimation of sleep. This study’s objective was to document sleep spindles characteristics in INS compared with GS and to investigate their potential role in sleep consolidation and misperception. Seventeen individuals with paradoxical insomnia (PARA-I), 24 individuals with psychophysiological insomnia (PSY-I), and 29 GS completed four consecutive polysomnographic nights in laboratory. Sleep spindles were detected automatically during stage 2 and SWS (3-4) on night 3. Number, density, duration, frequency, and amplitude of sleep spindles were calculated. A misperception index was used to determine the degree of discrepancy between subjective and objective total sleep times. Kruskal-Wallis H tests and post hoc tests revealed that PARA-I had significantly shorter sleep spindles than GS but that PSY-I and GS did not differ on spindles length. A standard multiple regression model revealed that neither sleep spindles characteristics nor objective sleep measures were predictive of sleep misperception. A longer duration of spindles could reflect a higher gating process but this hypothesis still needs to be confirmed in replication studies. [ABSTRACT FROM AUTHOR]

This project assessed the feasibility of in-lab dream collection in insomnia sufferers which have been limited, considering their reported sleep difficulties and heightened arousal. Eleven insomnia sufferers and 10 good sleepers underwent 5 consecutive polysomnography recording nights including 2 in-lab REM sleep full narrative dream collection. Dream recall frequency and sleep onset latency after each dream collection procedure were calculated. Analyses revealed no group effect (p=.14) for in-lab dream recall frequency (.96 for insomnia sufferers vs. .88 for good sleepers). Groups did not differ (p=.33) on sleep onset latency after dream collection. For sleep perception, insomnia individuals significantly underestimated their total sleep time at home (p≤.03) but not in the lab. Good sleepers correctly estimated their total sleep time at home but underestimated it in lab. For wake after sleep onset, insomnia sufferers correctly estimated it at home but underestimated it in the lab, while good sleepers underestimated it both at home and in the lab (p≤.02). These results suggest that in-lab full length dream collection can be successfully conducted with insomnia sufferers. Interestingly, dream collection also appeared to contribute to the underestimation of wake after sleep onset in insomnia individuals and good sleepers. It might be that externally induced awakenings attenuate the distress related to sleep difficulties especially in insomnia sufferers, since awakenings are attributed to dream collection. [ABSTRACT FROM AUTHOR]

Our objective was to investigate the physiological mechanisms involved in the sleep restriction treatment of insomnia. A multiple baseline across subjects design was used. Sleep of five participants suffering from insomnia was assessed throughout the experimentation by sleep diaries and actigraphy. Ten nights of polysomnography were conducted over five occasions. The first two-night assessment served to screen for sleep disorders and to establish a baseline for dependent measures. Three assessments were undertaken across the treatment interval, with the fifth and last one coming at follow-up. Daily cortisol assays were obtained. Sleep restriction therapy was applied in-lab for the first two nights of treatment and was subsequently supervised weekly. Interrupted time series analyses were computed on sleep diary data and showed a significantly decreased wake time, increasedsleep efficiency, and decreased total sleep time. Sleepiness at night seems positively related to sleep variables, polysomnography data suggest objective changes mainly for stage 2, and power spectral analysis shows a decrease in beta-1 and -2 powers for the second night of treatment. Cortisol levels seem to be lower during treatment. These preliminary results confirmpart of the proposed physiological mechanisms and suggest that sleep restriction contributes to a rapid decrease in hyperarousal insomnia. [ABSTRACT FROM AUTHOR]

Abstract: Preliminary QEEG studies suggest that individuals with paradoxical insomnia (Para-I) display higher cortical arousal than those with psychophysiological insomnia (Psy-I). Lately, finer measures, such as event-related potentials, and especially the N1 and P2 components have been used to document arousal processes in individuals with insomnia. The objective of the present study was to further circumscribe arousal in Psy-I and Para-I using N1, P2 and the waking processing negativity (wPN). N1 and P2 were recorded in the evening, at sleep-onset and in early stage 2 sleep in 26 good sleepers, 26 Psy-I and 26 Para-I. An oddball paradigm was used and participants received the instruction to ignore all stimuli at all times. Three difference waves (wPNs) were computed to evaluate the transition from wakefulness to sleep onset, from sleep onset to sleep and from wakefulness to sleep. Results revealed that N1 was smaller during wakefulness and sleep onset for Psy-I, while it was larger for Para-I during these same times. P2 was smaller at sleep onset for Psy-I than for Para-I and GS, while P2 during wakefulness and stage 2 sleep was larger for Para-I than GS. WPNs revealed that Psy-I showed fewer changes in information processing, while Para-I showed larger changes between recording times. Psy-I appear to present an inability to inhibit information processing during sleep onset, while Para-I seem to present overall enhanced attentional processing that results in a greater need for inhibition. [Copyright &y& Elsevier]

OBJECTIVES: A large body of literature documents the effects of prenatal exposure to polychlorinated biphenyls (PCBs) on cognitive development of children. Despite this fact, no integrative synthesis has been published yet to identify the cognitive functions that are particularly affected. Our aim is to review this literature in an attempt to identify the cognitive profile associated with prenatal PCB exposure. DATA SOURCES: Studies were identified by searching the PubMed database for articles published before June 2008. We reviewed data from nine prospective longitudinal birth cohorts for different aspects of cognition. DATA EXTRACTION: Associations between indicators of prenatal PCB exposure and performance on cognitive tasks reported in the selected studies are summarized and classified as general cognitive abilities, verbal or visual--spatial skills, memory, attention, and executive functions. DATA SYNTHESIS: The most consistent effects observed across studies are impaired executive functioning related to increased prenatal PCB exposure. Negative effects on processing speed, verbal abilities, and visual recognition memory are also reported by most studies. Converging results from different cohort studies in which exposure arises from different sources make it unlikely that co-exposure with another associated contaminant is responsible for the observed effects. CONCLUSION: Prenatal PCB exposure appears to be related to a relatively specific cognitive profile of impairments. Failure to assess functions that are specifically impaired may explain the absence of effects found in some studies. Our findings have implications in the selection of cognitive assessment methods in future studies. [ABSTRACT FROM AUTHOR]

Sleep of chronic insomniacs is often characterized by extensive night-to-night variability. To date, no study has examined this variability with long series of daily sleep data. The present study examined night-to-night variability with a sample of 106 participants meeting DSM-IV diagnostic criteria for persistent primary insomnia. Participants completed daily sleep diaries for an average of 31 days (range: 18–56). Sleep efficiency, sleep onset latency and wake after sleep onset were derived from this measure. Despite evidence of extensive night variability, results showed that sleep patterns could be classified in three clusters. The first one was characterized by a high probability of having poor sleep, the second one by a low and decreasing probability, and the third one by a constant median probability of having a poor sleep, which is an unpredictable sleep pattern. In the first cluster, poor sleep was expected each night for patients with a predominance mixed insomnia including the three insomnia subtypes. In the second cluster, patients presented moderate insomnia, sleep-onset latency below the threshold level and a predominance of sleep-maintenance insomnia. In the third pattern, poor nights seemed unpredictable for patients with moderate to severe insomnia associated with the lowest proportion of sleep-maintenance insomnia. Overall, sleep was predictable for about two-thirds of individuals, whereas it was unpredictable for about one-third. These findings confirm the presence of extensive variability in the sleep of chronic insomniacs and that poor sleep may be predictable for some of them. Additional research is needed to characterize those sleep patterns in terms of clinical features and temporal course. [ABSTRACT FROM AUTHOR]

Individuals with insomnia present unique patterns of electroencephalographic (EEG) asymmetry between homologous regions of each brain hemisphere, yet few studies have assessed asymmetry within the same hemisphere. Increase in intrahemispheric asymmetry during rapid eye movement (REM) sleep in good sleepers (GS) and disruption of REM sleep in insomnia sufferers (INS) both point out that this activity may be involved in the pathology of insomnia. The objective of the present exploratory study was to evaluate and quantify patterns of fronto-central, fronto-parietal, fronto-occipital, centro-parietal, centro-occipital and parieto-occipital intrahemispheric asymmetry in GS and INS, and to assess their association with sleep-wake misperception, daytime anxiety and depressive symptoms, as well as insomnia severity. This paper provides secondary analysis of standard EEG recorded in 43 INS and 19 GS for three nights in a sleep laboratory. Asymmetry measures were based on EEG power spectral analysis within 0.3–60 Hz computed between pairs of regions at frontal, central, parietal and occipital derivations. Repeated-measures ANOVAs were performed to assess group differences. Exploratory correlations were then performed on asymmetry and sleep-wake misperception, as well as self-reported daytime anxiety and depressive symptoms, and insomnia severity. INS presented increased delta and theta F3/P3 asymmetry during REM sleep compared with GS, positively associated with depressive and insomnia complaints. INS also exhibited decreased centro-occipital (C3/O1, C4/O2) and parieto-occipital (P3–O1, P4/O2) theta asymmetry during REM. These findings suggest that INS present specific patterns of intrahemispheric asymmetry, partially related to their clinical symptoms. Future studies may investigate the extent to which asymmetry is related to sleep-wake misperception or memory impairments. [ABSTRACT FROM AUTHOR]

Background and Objective: The dream activity of patients with primary insomnia (PI) has rarely been studied, especially using in-laboratory dream collection, although dreams could be linked to their state of hyperarousal and their negative waking experiences. The objective of the study was to compare patients with PI and good sleeper controls (GSCs) in terms of dream recall frequency and dream content.Patients/methods: Polysomnography was recorded in 12 patients with PI and 12 GSCs (aged between 30 and 45 years) for five consecutive nights. Rapid eye movement (REM) sleep awakenings were enforced on nights 3 and 5 for dream collections.Results: The REM dream collections revealed that the groups were similar in terms of dream recall frequency (p ≤ 0.7). With respect to dream content variables, the dreams of GSCs tended to comprise more positive emotions (p = 0.06), whereas the dreams of patients with PI were characterized by more negative elements than positive ones (p = 0.001). Subjectively, GSCs characterized their dreams as being more pleasant and containing more joy, happiness, and vividness (p ≤ 0.03) than patients with PI. Finally, elevated negative dream content was associated with lower sleep efficiencies in insomnia (p = 0.004).Conclusion: These results suggest that less positive emotions and greater negative content characterize the dreams of patients with PI, which is in line with their waking experiences. One potential explanation could be hyperarousal exacerbating presleep negative mentation, thus contributing to poorer sleep quality. The lack of difference in dream recall frequency is most likely due to the forced awakening "dream collection" procedure. The study of dream activity seems a promising avenue for understanding the 24-h experience of insomnia better and exploring the potential benefits of dream management techniques. [ABSTRACT FROM AUTHOR]

Study objectives The objective was to study REM sleep macrostructure and microstructure as potential indicators of hyperarousal in insomnia by comparing good sleepers (GS) and insomnia sufferers (INS) (subdivided into psychophysiological “PSY-I” and paradoxical “PARA-I”). Design Cross-sectional comparisons of GS, PSY-I and PARA-I. Setting Participants slept for 4 consecutive nights in the laboratory where PSG was recorded. Nights 2 and 3 were combined to compare REM sleep between groups. Participants Thirty-nine PSY-I, 27 PARA-I and 47 GS completed the study, comprising home questionnaires, clinical interviews and night PSG recordings. All participants were aged between 25 and 55 and met inclusion criteria for either PSY-I, PARA-I or GS. Interventions N/A. Measurements and results Results showed no between group differences on REM sleep macrostructure. As for REM sleep microstructure, PSY-I had an increased number of wake intrusions compared to PARA-I (p = .03). Subjective SE, TST and TWT were significantly correlated with the duration of REM sleep (REMD; p ≤ .002) and with the proportion of REM sleep for PARA-I (p ≤ .06). Conclusions REM sleep macrostructure does not seem to be an adequate indicator of hyperarousal in insomnia. However, the number of wake intrusions in REM could be used to differentiate PSY-I from PARA-I and could reflect the heightened arousal of the former group. Relationships between REM sleep duration and proportion could be linked to dream imagery activity, especially in PARA-I. Further investigations are needed to identify variables that could reflect hyperarousal and differentiate insomnia types. [ABSTRACT FROM AUTHOR]

Abstract: The objectives of the study were to examine EEG activities using power spectral analysis (PSA) of good sleepers (GS), psychophysiological (PsyI) and paradoxical (ParI) insomnia sufferers on two consecutive nights. Participants completed three nights of PSG recordings in a sleep laboratory following a clinical evaluation. Participants were 26 PsyI, 20 ParI and 21 GS (mean age=40years, SD=9.4). All sleep cycles of Nights 2 and 3 were retained for PSA. The absolute and relative activity in frequency bands (0.00 to 125.00Hz) were computed at multiple frontal, central and parietal sites in REM and NREM sleep. Mixed model ANOVAs were performed with absolute and relative PSA data to assess differences between groups and nights. Over the course of the two nights, more absolute delta activity at F3, C3, and P3 was observed in ParI compared with PsyI suggesting deactivation of the left hemisphere in ParI and/or hyperactivation in PsyI. Further analysis on absolute PSA data revealed that differences between groups relate mostly to NREM. In REM, lower relative activity in slower frequency bands was found in ParI in comparison with GS and less relative theta activity was found in PsyI compared with GS implying higher activation in insomnia. In addition, between nights variability has been found in absolute powers of faster frequency bands (beta to omega). Signs of decreased cortical activity in absolute PSA in NREM combined with increased relative cortical activation in REM were found in ParI which might contribute to the misperception of sleep in ParI. [Copyright &y& Elsevier]

Abstract: Despite Acute Insomnia being classified as a distinct nosological entity since 1979/1980 (ASDC/DSM III-R), there are no published estimates of its prevalence and incidence or data regarding transition to chronic insomnia or remission. This lack of data prevents an understanding of: a) the pathogenesis of insomnia and b) when and how treatment should be initiated. The aim of the present study was to provide such data from two community samples. Samples were recruited in the USA (n = 2861) and the North East of the UK (n = 1095). Additionally, 412 Normal Sleepers from the UK sample were surveyed longitudinally to determine prospectively incidence, transition, and remission rates for acute insomnia and assess whether the acute insomnia was a first episode, recurrent episode, or co-morbid with symptoms of other illnesses. The prevalence of acute insomnia was 9.5% (USA) and 7.9%(UK). The prevalence of three acute insomnia subtypes in the UK were; First-Onset Acute Insomnia 2.6%; Recurrent Acute Insomnia 3.8%; and 1.4% Co-morbid Acute Insomnia. The annual incidence of acute insomnia in the UK sample was between 31.2% and 36.6%. Remission rates fluctuated depending upon the definition of acute insomnia and whether the current episode was first-onset or recurrent. These findings provide preliminary insights into the natural history of insomnia. Such data will serve to inform how and when acute insomnia should be managed and whether such interventions may serve to diminish subsequent morbidity, particularly with respect to Major Depression. [Copyright &y& Elsevier]

Abstract: The event-related potential (ERP) P3b, a cognitive electrophysiological measure that has been linked to working memory processing in many experimental paradigms, was measured in Inuit children from Nunavik (Arctic Québec, Canada) to assess lead (Pb) neurotoxicity. Visual and auditory oddball paradigms were administered at 5 (N =27) and 11 (N =110) years of age, respectively, to elicit this ERP component. Pearson correlations and multiple regression analyses were performed to examine the associations between Pb levels and P3b parameters (peak latency and amplitude). Greater prenatal Pb exposure was related to a decrease in P3b amplitude at 5 years of age, and early childhood Pb exposure was associated with delayed P3b latency at 5 years. No significant association was observed at 11 years. These results, in line with those from previous neurobehavioral studies, suggest that Pb exposure affects cognitive processing in children even though the Pb levels measured in a large majority of our sample were below the threshold value for public health intervention used by federal agencies. This study strengthens the arguments for reducing sources of Pb exposure in Nunavik and for lowering the blood Pb concentrations considered “acceptable” in governmental policies. [Copyright &y& Elsevier]

To better understand Shift Work Disorder (SWD), this study investigates insomnia, sleepiness, and psychosocial features of night workers. The study compares night workers with or without SWD to day workers with or without insomnia. Seventy-nine night workers and 40 day workers underwent diagnostic interviews for sleep disorders and for psychopathologies. They completed questionnaires and a sleep diary for 14 days. The design was observatory upon two factors: Work schedule (night, day work) and sleep (good sleep, SWD/insomnia). Two-way ANCOVAs were conducted on psychosocial variables, and effect size were calculated. The clinical approach chosen led to distinct groups of workers. Night workers slept several periods (main sleep period after work, naps, nights on days off). High total wake time and low total sleep time characterized sleep in SWD. Most night workers with SWD still complained of sleepiness after main sleep. Cognitive activation distinguished groups of night workers. All other differences in psychosocial variables between night workers groups were similar to, but smaller than, the ones between day workers. The evaluation of SWD should consider all sleep periods of night workers with particular attention to self-reported total wake time, state sleepiness, and level of cognitive activation. [ABSTRACT FROM AUTHOR]

Nearly one-third of the population reports new onset or acute insomnia in a given year. Similarly, it is estimated that approximately 10% of the population endorses sleep initiation and maintenance problems consistent with diagnostic criteria for chronic insomnia. For decades, acute and chronic insomnia have been considered variations of the same condition or disorder, only really differentiated in terms of chronicity of symptoms (days/weeks versus months). Whether or not acute and chronic insomnia are part of the same phenomena is an important question, one that has yet to be empirically evaluated. The goal of the present theoretical review was to summarize the definitions of acute and chronic insomnia and discuss the role that hyperarousal may have in explaining how the pathophysiology of acute and chronic insomnia is likely different (i.e., what biopsychological factors precipitate and/or perpetuate acute insomnia, chronic insomnia, or both?). [ABSTRACT FROM AUTHOR]