Search

Study Objectives: Apolipoprotein E ɛ4 (APOE4) is the strongest genetic risk factor for Alzheimer's disease (AD). In addition, APOE4 carriers may exhibit sleep disturbances, but conflicting results have been reported, such that there is no clear consensus regarding which aspects of sleep are impacted. Our objective was to compare objective sleep architecture between APOE4 carriers and non-carriers, and to investigate the modulating impact of age, sex, cognitive status, and obstructive sleep apnea (OSA)., Methods: A total of 198 dementia-free participants aged >55 years old (mean age: 68.7 ± 8.08 years old, 40.91% women, 41 APOE4 carriers) were recruited in this cross-sectional study. They underwent polysomnography, APOE4 genotyping, and a neuropsychological evaluation. ANCOVAs assessed the effect of APOE4 status on sleep architecture, controlling for age, sex, cognitive status, and the apnea-hypopnea index. Interaction terms were added between APOE4 status and covariates., Results: Rapid eye movement (REM) sleep percentage (F = 9.95, p = .002, ηp2 = 0.049) and duration (F = 9.23, p = .003, ηp2 = 0.047) were lower in APOE4 carriers. The results were replicated in a subsample of 112 participants without moderate-to-severe OSA. There were no significant interactions between APOE4 status and age, sex, cognitive status, and OSA in the whole sample., Conclusions: Our results show that APOE4 carriers exhibit lower REM sleep duration, including in cognitively unimpaired individuals, possibly resulting from early neurodegenerative processes in regions involved in REM sleep generation and maintenance., (© The Author(s) 2024. Published by Oxford University Press on behalf of Sleep Research Society.)

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]

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]

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]

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]

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: 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]

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]