Decreased Delta/Beta ratio index as the sleep state-independent electrophysiological signature of sleep state misperception in Insomnia disorder: A focus on the sleep onset and the whole night.

PURPOSE: Sleep State Misperception (SSM) is described as the tendency of Insomnia Disorder (ID) patients to overestimate Sleep Latency (SL) and underestimate Total Sleep Time (TST). Literature exploring topographical components in ID with SSM is scarce and does not allow us to fully understand the potential mechanisms underlying this phenomenon. This study aims to evaluate the existence of sleep EEG topography alterations in ID patients associated with SSM compared to Healthy Controls (HC), focusing on two distinct periods: the Sleep Onset (SO) and the whole night. METHODS: Twenty ID patients (mean age: 43.5 ± 12.7; 7 M/13F) and 18 HCs (mean age: 41.6 ± 11.9; 8 M/10F) underwent a night of Polysomnography (PSG) and completed sleep diaries the following morning upon awakening. Two SSM indices, referring to the misperception of SL (SLm) and TST (TSTm), were calculated by comparing objective and subjective sleep indices extracted by PSG and sleep diary. According to these indices, the entire sample was split into 4 sub-groups: ID +SLm vs HC -SLm; ID +TSTm vs HC -TSTm. RESULTS: Considering the SO, the two-way mixed-design ANOVA showed a significant main effect of Groups pointing to a decreased delta/beta ratio in the whole scalp topography. Moreover, we found a significant interaction effect for the sigma and beta bands. Post Hoc tests showed higher sigma and beta power in anterior and temporo-parietal sites during the SO period in IDs +SLm compared to HC -SLm. Considering the whole night, the unpaired t-test revealed in IDs +TSTm significantly lower delta power during NREM, and lower delta/beta ratio index during NREM and REM sleep compared to HCs -TSTm. Finally, we found diffuse significant negative correlations between SSM indices and the delta/beta ratio during SO, NREM, and REM sleep. CONCLUSION: The main finding of the present study suggests that higher SL overestimation and TST underestimation are both phenomena related to diffuse cortical hyperarousal interpreted as a sleep state-independent electrophysiological correlate of the SSM, both during the SO and the whole night.

Associations between obesity, a composite risk score for probable long COVID, and sleep problems in SARS-CoV-2 vaccinated individuals.

BACKGROUND: Preliminary data suggests that obesity might hasten the decline in mRNA vaccine-induced immunity against SARS-CoV-2. However, whether this renders individuals with obesity more susceptible to long COVID symptoms post-vaccination remains uncertain. Given sleep's critical role in immunity, exploring the associations between obesity, probable long COVID symptoms, and sleep disturbances is essential. METHODS: We analyzed data from a survey of 5919 adults aged 18 to 89, all of whom received two SARS-CoV-2 mRNA vaccinations. Participants were categorized into normal weight, overweight, and obesity groups based on ethnicity-specific BMI cutoffs. The probability of long COVID was evaluated using the Post-Acute Sequelae of SARS-CoV-2 (PASC) score, as our survey did not permit confirmation of acute SARS-CoV-2 infection through methods such as antibody testing. Additionally, sleep patterns were assessed through questionnaires. RESULTS: Participants with obesity exhibited a significantly higher adjusted odds ratio (OR) of having a PASC score of 12 or higher, indicative of probable long COVID in our study, compared to those with normal weight (OR: 1.55, 95% CI: 1.05, 2.28). No significant difference was observed for overweight individuals (OR: 0.92 [95% CI: 0.63, 1.33]). Both obesity and probable long COVID were associated with increased odds of experiencing a heightened sleep burden, such as the presence of obstructive sleep apnea or insomnia (P < 0.001). However, no significant interaction between BMI and probable long COVID status was found. CONCLUSIONS: Even post-vaccination, individuals with obesity may encounter a heightened risk of experiencing prolonged COVID-19 symptoms. However, confirming our observations necessitates comprehensive studies incorporating rigorous COVID infection testing, such as antibody assays - unavailable in our anonymous survey. Additionally, it is noteworthy that the correlation between probable long COVID and sleep disturbances appears to be independent of BMI.

The role of the sleep K-complex on the conversion from mild cognitive impairment to Alzheimer's disease.

The present literature points to an alteration of the human K-complex during non-rapid eye movement sleep in Alzheimer's disease. Nevertheless, the few findings on the K-complex changes in mild cognitive impairment and their possible predictive role on the Alzheimer's disease conversion show mixed findings, lack of replication, and a main interest for the frontal region. The aim of the present study was to assess K-complex measures in amnesic mild cognitive impairment subsequently converted in Alzheimer's disease over different cortical regions, comparing them with healthy controls and stable amnesic mild cognitive impairment. We assessed baseline K-complex density, amplitude, area under the curve and overnight changes in frontal, central and parietal midline derivations of 12 amnesic mild cognitive impairment subsequently converted in Alzheimer's disease, 12 stable amnesic mild cognitive impairment and 12 healthy controls. We also assessed delta electroencephalogram power, to determine if K-complex alterations in amnesic mild cognitive impairment occur with modification of the electroencephalogram power in the frequency range of the slow-wave activity. We found a reduced parietal K-complex density in amnesic mild cognitive impairment subsequently converted in Alzheimer's disease compared with stable amnesic mild cognitive impairment and healthy controls, without changes in K-complex morphology and overnight modulation. Both amnesic mild cognitive impairment groups showed decreased slow-wave sleep percentage compared with healthy controls. No differences between groups were observed in slow-wave activity power. Our findings suggest that K-complex alterations in mild cognitive impairment may be observed earlier in parietal regions, likely mirroring the topographical progression of Alzheimer's disease-related brain pathology, and express a frontal predominance only in a full-blown phase of Alzheimer's disease. Consistently with previous results, such K-complex modification occurs in the absence of significant electroencephalogram power changes in the slow oscillations range.

Nightmare frequency is a risk factor for suicidal ideation during the COVID-19 pandemic.

The association between nightmare frequency (NMF) and suicidal ideation (SI) is well known, yet the impact of the COVID-19 pandemic on this relation is inconsistent. This study aimed to investigate changes in NMF, SI, and their association during the COVID-19 pandemic. Data were collected in 16 countries using a harmonised questionnaire. The sample included 9328 individuals (4848 women; age M[SD] = 46.85 [17.75] years), and 17.60% reported previous COVID-19. Overall, SI was significantly 2% lower during the pandemic vs. before, and this was consistent across genders and ages. Most countries/regions demonstrated decreases in SI during this pandemic, with Austria (-9.57%), Sweden (-6.18%), and Bulgaria (-5.14%) exhibiting significant declines in SI, but Italy (1.45%) and Portugal (2.45%) demonstrated non-significant increases. Suicidal ideation was more common in participants with long-COVID (21.10%) vs. short-COVID (12.40%), though SI did not vary by COVID-19 history. Nightmare frequency increased by 4.50% during the pandemic and was significantly higher in those with previous COVID-19 (14.50% vs. 10.70%), during infection (23.00% vs. 8.10%), and in those with long-COVID (18.00% vs. 8.50%). The relation between NMF and SI was not significantly stronger during the pandemic than prior (rs = 0.18 vs. 0.14; z = 2.80). Frequent nightmares during the pandemic increased the likelihood of reporting SI (OR = 1.57, 95% CI 1.20-2.05), while frequent dream recall during the pandemic served a protective effect (OR = 0.74, 95% CI 0.59-0.94). These findings have important implications for identifying those at risk of suicide and may offer a potential pathway for suicide prevention.

Exploring the role of dreams: insights from recent studies.

PURPOSE OF REVIEW: Dreaming has only recently become a topic of scientific research. This review updates current findings on dream studies, emphasizing recent research on the neural mechanisms of dreaming. Additionally, it summarizes new evidence on the functional role of dreams, including insights from studies on dreams and nightmares during the coronavirus disease 2019 (COVID-19) pandemic. RECENT FINDINGS: Recent advances on the neural basis of mental activity during sleep have shifted towards dream-related phenomena, such as dream experiences in relation to parasomnias and hypnagogic hallucinations. Although some findings are consistent with the main models explaining dream recall (i.e., continuity hypothesis; activation hypothesis), some results contrast with the role of parieto-occipital region in dream experience. Moreover, recent findings - related to COVID-19 pandemic - underlined that dream experiences could express emotion regulation processes as well as provide a simulation of reality to prepare for future dangerous or social interactions. SUMMARY: Overall, we highlighted the intricate interplay between brain regions in dreaming and suggest that dreams serve multiple functions, from reflecting waking-life experiences to simulating adaptive responses to threats. Understanding the neural bases and functions of dreaming can provide valuable insights into human mental health, nevertheless, further research is needed.

A systematic review of dreams and nightmares recall in patients with rapid eye movement sleep behaviour disorder.

Rapid eye movement (REM) sleep behaviour disorder is a REM sleep parasomnia characterised by the loss of the physiological muscle atonia during REM sleep, resulting in dream enactment behaviours that may cause injuries to patients or their bed partners. The nocturnal motor episodes seem to respond to the dream contents, which are often vivid and violent. These behavioural and oneiric features make the REM sleep behaviour disorder a potential model to study dreams. This review aims to unify the literature about dream recall in REM sleep behaviour disorder as a privileged approach to study dreams, systematically reviewing studies that applied retrospective and prospective experimental designs to provide a comprehensive overview of qualitative and quantitative aspects of dream recall in this REM sleep parasomnia. The present work highlights that the study of dreaming in REM sleep behaviour disorder is useful to understand unique aspects of this pathology and to explore neurobiological, electrophysiological, and cognitive mechanisms of REM sleep and dreaming.

Poor sleep hygiene practices are associated with a higher increase in sleep problems during the COVID-19 pandemic: A latent change score model.

The Coronavirus 2019 (COVID-19) pandemic significantly influenced physical and mental health worldwide. The present study aimed to investigate changes in sleep problems across three waves of the COVID-19 pandemic, and to identify potential predictors of the inter-individual variability around these changes, with a particular focus on the role of detrimental sleep hygiene practices. A total of 352 participants completed an online survey of self-report questionnaires at three different waves of the COVID-19 pandemic: T1 (Spring 2020); T2 (Autumn-Winter 2020); and T3 (Spring 2021). The questionnaires collected information on socio-demographic and COVID-19-related variables, psychological distress (i.e. the Depression Anxiety Stress Scale-21), sleep hygiene (i.e. the Sleep Hygiene Index) and sleep problems (i.e. the Medical Outcomes Study-Sleep Scale). Latent change score modelling revealed an average increase in sleep problems between T1 and T2 with significant inter-individual variability. No substantial changes were observed on average between T2 and T3. Notably, poorer sleep hygiene practices were associated with a more pronounced increase in sleep problems between T1 and T2 (ß = 0.191, p = 0.013), even after controlling for relevant confounders such as demographic factors, COVID-19-related information and psychological distress. These findings expand on previous research regarding the detrimental effects of the pandemic on mental health, suggesting that interventions targeting sleep hygiene practices may be beneficial for mitigating its negative impact on sleep disruptions.

'This is the last episode': the association between problematic binge-watching and loneliness, emotion regulation, and sleep-related factors in poor sleepers.

Evidence on the relation between binge-watching and sleep quality is still scarce and inconsistent and none has taken into account both the healthy and pathological dimensions of the phenomenon. This study aimed at filling this gap by investigating both aspects in healthy participants with high and low sleep quality. Further, we aimed at identifying sociodemographic, psychological and sleep-related determinants of problematic binge-watching in poor sleepers. We first conducted independent comparisons between good (n = 253) and poor sleepers (n = 209) on different binge-watching symptoms and motives, assessed through 'Binge-watching Engagement and Symptoms' and 'Watching TV Series Motives' questionnaires, respectively. Then, we focused on the problematic aspects of binge-watching in poor sleepers, investigating the role of emotion regulation, loneliness, and sleep-related factors using hierarchical multiple regressions. Comparisons between the two groups revealed a greater extent of binge-watching behaviour (t = -2.80, p = 0.005) and greater use of this practise to cope with negative emotions (t = -4.17, p < 0.001) in poor sleepers. In addition, hierarchical multiple regressions showed that gender (ß = -0.166, p = 0.008), alcohol consumption (ß = -0.135, p = 0.035), emotional dysregulation (ß = 0.260, p = 0.001; ß = 0.298, p < 0.001), feelings of loneliness (ß = 0.159, p = 0.029; ß = 0.199, p = 0.003), and daytime sleepiness (ß = 0.149, p = 0.016) are significant determinants of problematic binge-watching in this population. In addition to showing for the first time the relationship between sleep quality and different aspects of binge-watching, our findings indicate that emotional dysregulation, feelings of loneliness, and daytime sleepiness play a key role in determining problematic binge-watching in poor sleepers, possibly due to the existence of a pathological vicious circle between these factors in poor sleepers.

Challenging subjective excessive daytime sleepiness as an insomnia symptom: a retrospective study.

Diagnostic manuals describe insomnia disorder (ID) characterised by fatigue and sleepiness as diurnal consequences of nocturnal symptoms. However, patients with ID do not frequently report sleepiness in the clinical setting. The present study aimed to investigate subjective sleepiness in ID measured through the Epworth Sleepiness Scale (ESS) and its independence towards daytime functioning and fatigue, and to evaluate cognitive behavioural therapy for insomnia (CBT-I) improvement in daytime consequences and their relationship to sleepiness and fatigue. We retrospectively collected the ESS evaluation in a large sample of 105 healthy controls (HCs), 671 patients with ID, and 602 patients with sleep disorders characterised by excessive daytime sleepiness (EDS). Moreover, we conducted a pre-post evaluation of the ESS in a sub-sample of patients with ID who underwent CBT-I. Component 2 of the Insomnia Severity Index and Profile of Mood States-Fatigue Inertia Scale was used to evaluate daytime functioning and fatigue. Patients with ID reported ESS levels comparable to that observed in HCs and significantly lower than the EDS group. No significant correlation arose between ESS and the diurnal impact of the disorder, suggesting the independence between daytime functioning and sleepiness in ID. Contrarily, insomnia severity and diurnal impact significantly correlated with fatigue. Data showed a statistically significant increase in sleepiness after CBT-I, despite significantly improving daytime consequences and fatigue. Although diagnostic manuals report sleepiness and fatigue as daytime consequences of sleep symptoms in patients with ID, these retrospective data indicate a dissociation between these entities. This evidence aligns with the core feature of ID: the hyperarousal status that pervades patients also during wakefulness.

The effects of bifrontal anodal transcranial direct current stimulation (tDCS) on sleepiness and vigilance in partially sleep-deprived subjects: A multidimensional study.

In recent years, transcranial electrical stimulation techniques have demonstrated their ability to modulate our levels of sleepiness and vigilance. However, the outcomes differ among the specific aspects considered (physiological, behavioural or subjective). This study aimed to observe the effects of bifrontal anodal transcranial direct current stimulation. Specifically, we tested the ability of this stimulation protocol to reduce sleepiness and increase vigilance in partially sleep-deprived healthy participants. Twenty-three subjects underwent a within-subject sham-controlled stimulation protocol. We compared sleepiness and vigilance levels before and after the two stimulation conditions (active versus sham) by using behavioural (reaction-time task), subjective (self-report scales) and physiological (sleep-onset latency and electroencephalogram power [n = 20] during the Maintenance of Wakefulness Test) measures. We showed the efficacy of the active stimulation in reducing physiological sleepiness and preventing vigilance drop compared with the sham stimulation. Consistently, we observed a reduction of perceived sleepiness following the active stimulation for both self-report scales. However, the stimulation effect on subjective measures was not statistically significant probably due to the underpowered sample size for these measures, and to the possible influence of motivational and environmental factors. Our findings confirm the ability of this technique to influence vigilance and sleepiness, pointing out the potential for new treatment developments based on transcranial electrical stimulation.