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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., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

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., (© 2024 European Sleep Research Society.)

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., (© 2024. The Author(s).)

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 (β = 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., (© 2023 The Authors. Journal of Sleep Research published by John Wiley & Sons Ltd on behalf of European Sleep Research Society.)

Study Objectives: Preliminary evidence suggests that the risk of Long COVID is higher among people with pre-existing medical conditions. Based on its proven adjuvant role in immunity, habitual sleep duration may alter the risk of developing Long COVID. The objective of this study was to determine whether the odds of Long COVID are higher among those with pre-existing medical conditions, and whether the strength of this association varies by habitual sleep duration., Methods: Using data from 13,461 respondents from 16 countries who participated in the 2021 survey-based International COVID Sleep Study II (ICOSS II), we studied the associations between habitual sleep duration, pre-existing medical conditions, and Long COVID., Results: Of 2,508 individuals who had COVID-19, 61% reported at least 1 Long COVID symptom. Multivariable logistic regression analysis showed that the risk of having Long COVID was 1.8-fold higher for average-length sleepers (6-9 h/night) with pre-existing medical conditions compared with those without pre-existing medical conditions (adjusted odds ratio [aOR] 1.84 [1.18-2.90]; P = .008). The risk of Long COVID was 3-fold higher for short sleepers with pre-existing medical conditions (aOR 2.95 [1.04-8.4]; P = .043) and not significantly higher for long sleepers with pre-existing conditions (aOR 2.11 [0.93-4.77]; P = .073) compared with average-length sleepers without pre-existing conditions., Conclusions: Habitual short nighttime sleep duration exacerbated the risk of Long COVID in individuals with pre-existing conditions. Restoring nighttime sleep to average duration represents a potentially modifiable behavioral factor to lower the odds of Long COVID for at-risk patients., Citation: Berezin L, Waseem R, Merikanto I, et al. Habitual short sleepers with pre-existing medical conditions are at higher risk of long COVID. J Clin Sleep Med . 2024;20(1):111-119., (© 2024 American Academy of Sleep Medicine.)

Objective: There is evidence of a strong association between insomnia and COVID-19, yet few studies have examined the relationship between insomnia and long COVID. This study aimed to investigate whether COVID-19 patients with pre-pandemic insomnia have a greater risk of developing long COVID and whether long COVID is in turn associated with higher incident rates of insomnia symptoms after infection., Methods: Data were collected cross-sectionally (May-Dec 2021) as part of an international collaborative study involving participants from 16 countries. A total of 2311 participants (18-99 years old) with COVID-19 provided valid responses to a web-based survey about sleep, insomnia, and health-related variables. Log-binomial regression was used to assess bidirectional associations between insomnia and long COVID. Analyses were adjusted for age, sex, and health conditions, including sleep apnea, attention and memory problems, chronic fatigue, depression, and anxiety., Results: COVID-19 patients with pre-pandemic insomnia showed a higher risk of developing long COVID than those without pre-pandemic insomnia (70.8% vs 51.4%; adjusted relative risk [RR]: 1.33, 95% confidence interval [CI]: 1.07-1.65). Among COVID-19 cases without pre-pandemic insomnia, the rates of incident insomnia symptoms after infection were 24.1% for short COVID cases and 60.6% for long COVID cases (p < .001). Compared with short COVID cases, long COVID cases were associated with an increased risk of developing insomnia symptoms (adjusted RR: 2.00; 95% CI: 1.50-2.66)., Conclusions: The findings support a bidirectional relationship between insomnia and long COVID. These findings highlight the importance of addressing sleep and insomnia in the prevention and management of long COVID., Competing Interests: Declaration of competing interest Authors declare none., (Crown Copyright © 2023. Published by Elsevier B.V. All rights reserved.)

Background: Self-rated health (SRH) is widely recognized as a clinically significant predictor of subsequent mortality risk. Although COVID-19 may impair SRH, this relationship has not been extensively examined. The present study aimed to examine the correlation between habitual sleep duration, changes in sleep duration after infection, and SRH in subjects who have experienced SARS-CoV-2 infection., Methods: Participants from 16 countries participated in the International COVID Sleep Study-II (ICOSS-II) online survey in 2021. A total of 10,794 of these participants were included in the analysis, including 1,509 COVID-19 individuals (who reported that they had tested positive for COVID-19). SRH was evaluated using a 0-100 linear visual analog scale. Habitual sleep durations of < 6 h and > 9 h were defined as short and long habitual sleep duration, respectively. Changes in habitual sleep duration after infection of ≤ -2 h and ≥ 1 h were defined as decreased or increased, respectively., Results: Participants with COVID-19 had lower SRH scores than non-infected participants, and those with more severe COVID-19 had a tendency towards even lower SRH scores. In a multivariate regression analysis of participants who had experienced COVID-19, both decreased and increased habitual sleep duration after infection were significantly associated with lower SRH after controlling for sleep quality (β = -0.056 and -0.058, respectively, both p < 0.05); however, associations between current short or long habitual sleep duration and SRH were negligible. Multinomial logistic regression analysis showed that decreased habitual sleep duration was significantly related to increased fatigue (odds ratio [OR] = 1.824, p < 0.01), shortness of breath (OR = 1.725, p < 0.05), diarrhea/nausea/vomiting (OR = 2.636, p < 0.01), and hallucinations (OR = 5.091, p < 0.05), while increased habitual sleep duration was significantly related to increased fatigue (OR = 1.900, p < 0.01)., Conclusions: Changes in habitual sleep duration following SARS-CoV-2 infection were associated with lower SRH. Decreased or increased habitual sleep duration might have a bidirectional relation with post-COVID-19 symptoms. Further research is needed to better understand the mechanisms underlying these relationships for in order to improve SRH in individuals with COVID-19., (© 2023. The Author(s).)

Background: The COVID-19 pandemic and related restriction measures have affected our daily life, sleep, and circadian rhythms worldwide. Their effects on hypersomnolence and fatigue remain unclear., Methods: The International COVID-19 Sleep Study questionnaire which included items on hypersomnolence such as excessive daytime sleepiness (EDS), and excessive quantity of sleep (EQS), as well as sociodemographic factors, sleep patterns, psychological symptoms, and quality of life was distributed in 15 countries across the world from May to September in 2020., Results: Altogether responses from 18,785 survey participants (65% women, median age 39 years) were available for analysis. Only 2.8% reported having had COVID-19. Compared to before the pandemic, the prevalence of EDS, EQS, and fatigue increased from 17.9% to 25.5%, 1.6%-4.9%, and 19.4%-28.3% amid the pandemic, respectively. In univariate logistic regression models, reports of having a COVID-19 were associated with EQS (OR 5.3; 95%-CI 3.6-8.0), EDS (2.6; 2.0-3.4), and fatigue (2.8; 2.1-3.6). In adjusted multivariate logistic regression, sleep duration shorter than desired (3.9; 3.2-4.7), depressive symptoms (3.1; 2.7-3.5), use of hypnotics (2.3; 1.9-2.8), and having reported COVID-19 (1.9; 1.3-2.6) remained strong predictors of EDS. Similar associations emerged for fatigue. In the multivariate model, depressive symptoms (4.1; 3.6-4.6) and reports of having COVID-19 (2.0; 1.4-2.8) remained associated with EQS., Conclusions: A large increase in EDS, EQS, and fatigue occurred due to the COVID-19 pandemic, and especially in self-reported cases of COVID-19. These findings warrant a thorough understanding of their pathophysiology to target prevention and treatment strategies for long COVID condition., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Author(s). Published by Elsevier B.V. All rights reserved.)

Recent investigations show that many people affected by SARS-CoV2 (COVID-19) report persistent symptoms 2-3 months from the onset of the infection. Here, we report the Italian findings from the second International COVID-19 Sleep Study survey, aiming to investigate sleep and dream alterations in participants with post-acute symptoms, and identify the best determinants of these alterations among patients with long-COVID. Data from 383 participants who have had COVID-19 were collected through a web-survey (May-November 2021). Descriptive analyses were performed to outline the sociodemographic characteristics of long-COVID (N = 270, with at least two long-lasting symptoms) and short-COVID (N = 113, with none or one long-lasting symptom) participants. They were then compared concerning sleep and dream measures. We performed multiple linear regressions considering as dependent variables sleep and dream parameters discriminating the long-COVID group. Age, gender, work status, financial burden, COVID-19 severity and the level of care were significantly different between long-COVID and short-COVID subjects. The long-COVID group showed greater sleep alterations (sleep quality, daytime sleepiness, sleep inertia, naps, insomnia, sleep apnea, nightmares) compared with the short-COVID group. We also found that the number of long-COVID symptoms, psychological factors and age were the best explanatory variables of sleep and oneiric alterations. Our findings highlight that sleep alterations are part of the clinical presentation of the long-COVID syndrome. Moreover, psychological status and the number of post-acute symptoms should be considered as state-like variables modulating the sleep problems in long-COVID individuals. Finally, according to previous investigations, oneiric alterations are confirmed as a reliable mental health index., (© 2022 European Sleep Research Society.)

The present study had two main aims. First, to investigate whether shift/night workers had a higher prevalence and severity of COVID-19 compared with day workers. Second, to investigate whether people regularly working in face-to-face settings during the pandemic exhibited a higher prevalence and severity of COVID-19 compared with those having no need to be in close contact with others at work. Data consisted of 7141 workers from 15 countries and four continents who participated in the International COVID Sleep Study-II (ICOSS-II) between May and December 2021. The associations between work status and a positive COVID-19 test and several indications of disease severity were tested with chi-square tests and logistic regressions adjusted for relevant confounders. In addition, statistical analyses were conducted for the associations between face-to-face work and COVID-19 status. Results showed that shift/night work was not associated with an increased risk of COVID-19 compared to day work. Still, shift/night workers reported higher odds for moderate to life-threatening COVID-19 (adjusted odds ratio (aOR) = 2.71, 95%-confidence interval = 1.23-5.95) and need for hospital care (aOR = 5.66, 1.89-16.95). Face-to-face work was associated with an increased risk of COVID-19 (aOR = 1.55, 1.12-2.14) but not with higher disease severity. In conclusion, shift/night work was not associated with an increased risk of COVID-19, but when infected, shift/night workers reported more severe disease. Impaired sleep and circadian disruption commonly seen among shift/night workers may be mediating factors. Working face-to-face increased the risk of COVID-19, likely due to increased exposure to the virus. However, face-to-face work was not associated with increased disease severity.

There has been increasing concern about the long-term impact of coronavirus disease 2019 (COVID-19) as evidenced by anecdotal case reports of acute-onset parkinsonism and the polysomnographic feature of increased rapid eye movement sleep electromyographic activity. This study aimed to determine the prevalence and correlates of dream-enactment behaviours, a hallmark of rapid eye movement sleep behaviour disorder, which is a prodrome of α-synucleinopathy. This online survey was conducted between May and August 2020 in 15 countries/regions targeting adult participants (aged ≥18 years) from the general population with a harmonised structured questionnaire on sleep patterns and disorders, COVID-19 diagnosis and symptoms. We assessed dream-enactment behaviours using the Rapid Eye Movement Sleep Behaviour Disorder Single-Question Screen with an additional question on their frequency. Among 26,539 respondents, 21,870 (82.2%) answered all items that were analysed in this study (mean [SD] age 41.6 [15.8] years; female sex 65.5%). The weighted prevalence of lifetime and weekly dream-enactment behaviours was 19.4% and 3.1% and were found to be 1.8- and 2.9-times higher in COVID-19-positive cases, respectively. Both lifetime and weekly dream-enactment behaviours were associated with young age, male sex, smoking, alcohol consumption, higher physical activity level, nightmares, COVID-19 diagnosis, olfactory impairment, obstructive sleep apnea symptoms, mood, and post-traumatic stress disorder features. Among COVID-19-positive cases, weekly dream-enactment behaviours were positively associated with the severity of COVID-19. Dream-enactment behaviours are common among the general population during the COVID-19 pandemic and further increase among patients with COVID-19. Further studies are needed to investigate the potential neurodegenerative effect of COVID-19., (© 2022 European Sleep Research Society.)

Short nighttime sleep duration impairs the immune response to virus vaccination, and long nighttime sleep duration is associated with poor health status. Thus, we hypothesized that short (<6 h) and long (>9 h) nighttime sleepers have a higher post-COVID risk than normal nighttime sleepers, despite two doses of mRNA vaccine (which has previously been linked to lower odds of long-lasting COVID-19 symptoms). Post-COVID was defined as experiencing at least one core COVID-19 symptom for at least three months (e.g., shortness of breath). Multivariate logistic regression adjusting for age, sex, BMI, and other factors showed in 9717 respondents (age span 18-99) that two mRNA vaccinations lowered the risk of suffering from post-COVID by about 21% (p < 0.001). When restricting the analysis to double-vaccinated respondents (n = 5918), short and long sleepers exhibited a greater post-COVID risk than normal sleepers (adjusted OR [95%-CI], 1.56 [1.29, 1.88] and 1.87 [1.32, 2.66], respectively). Among respondents with persistent sleep duration patterns during the pandemic compared to before the pandemic, short but not long sleep duration was significantly associated with the post-COVID risk (adjusted OR [95%-CI], 1.59 [1.24, 2.03] and 1.18 [0.70, 1.97], respectively). No significant association between sleep duration and post-COVID symptoms was observed in those reporting positive SARS-CoV-2 test results (n = 538). Our findings suggest that two mRNA vaccinations against SARS-CoV-2 are associated with a lower post-COVID risk. However, this protection may be less pronounced among those sleeping less than 6 h per night. Our findings warrant replication in cohorts with individuals with confirmed SARS-CoV-2 infection., (© 2023. The Author(s).)

Many people report suffering from post-acute sequelae of COVID-19 or "long-COVID", but there are still open questions on what actually constitutes long-COVID and how prevalent it is. The current definition of post-acute sequelae of COVID-19 is based on voting using the Delphi-method by the WHO post-COVID-19 working group. It emphasizes long-lasting fatigue, shortness of breath and cognitive dysfunction as the core symptoms of post-acute sequelae of COVID-19. In this international survey study consisting of 13,628 subjects aged 18-99 years from 16 countries of Asia, Europe, North America and South America (May-Dec 2021), we show that post-acute sequelae of COVID-19 symptoms were more prevalent amongst the more severe COVID-19 cases, i.e. those requiring hospitalisation for COVID-19. We also found that long-lasting sleep symptoms are at the core of post-acute sequelae of COVID-19 and associate with the COVID-19 severity when COVID-19 cases are compared with COVID-negative cases. Specifically, fatigue (61.3%), insomnia symptoms (49.6%) and excessive daytime sleepiness (35.8%) were highly prevalent amongst respondents reporting long-lasting symptoms after hospitalisation for COVID-19. Understanding the importance of sleep-related symptoms in post-acute sequelae of COVID-19 has a clinical relevance when diagnosing and treating long-COVID., (© 2022 The Authors. Journal of Sleep Research published by John Wiley & Sons Ltd on behalf of European Sleep Research Society.)

COVID-19 has challenged the health workforce worldwide. In this cross-sectional study with a retrospective assessment, we explored the impact of the pandemic on mental health and sleep among a sample of Italian nurses and medical doctors. A total of 287 healthcare workers (212 nurses and 75 physicians) completed a web survey on socio-demographic, psychological, and sleep-related aspects referring to the period before the pandemic and to the present period of February to June 2022. Comparisons between nurses and physicians revealed that the former had greater distress in response to the pandemic. Consistently, the multivariate analysis of covariance showed that even if both groups were negatively impacted by the pandemic, nurses presented a greater worsening over time regarding several psychological and sleep symptoms. Furthermore, we observed that working on the frontline represented an additional risk factor for nurses. In line with previous evidence, we also found that personal experiences with COVID-19 are significant predictors of the current health status. Our results underscore the urgent need for preventive programs among healthcare operators to increase their coping skills and prevent the long-term consequences of chronic stress, especially for high-risk professionals. Specific attention should also be devoted to programs to improve sleep quality and reduce sleep-related traumatic symptoms.

This protocol paper describes the second survey produced by the International Covid Sleep Study (ICOSS) group with the aim to examine the associations between SARS-CoV-2 infection and sleep, sleepiness, and circadian problems as potential predisposing factors for more severe COVID-19 disease profile and for development of Long-COVID in the general population. The survey consists of 47 questions on sleep, daytime sleepiness, circadian rhythm, health, mental wellbeing, life habits, and socioeconomic situation before and during the pandemic, and conditional questions to those reporting having had coronavirus infection, being vaccinated, or suffering from particular sleep symptoms or sleep disorders. Surveys will be administered online between May and November 2021 in Austria, Brazil, Bulgaria, Canada, China, Croatia, Finland, France, Germany, Israel, Italy, Japan, Norway, Portugal, Sweden and USA. Data collected by the survey will give valuable information on the open questions regarding COVID-19 disease risk factors, symptomatology and evolution of Long-COVID, and on other long-term consequences related to the pandemic., (© 2021 European Sleep Research Society.)

According to several influential models, dreams can be affected by state- and trait-like factors, sleep features, and diurnal experiences. The COVID-19 pandemic globally affected daily habits, emotional experiences, and sleep. Previous studies suggested an influence of collective traumatic events on dreaming. Starting from these premises, several studies assessed the effect of the pandemic on dreams. This paper aims to review findings concerning the oneiric activity during the COVID-19 pandemic. We report pandemic-related changes in dreams and nightmares, and we consider the possible factors associated with dreaming. Moreover, we provide results about changes in the oneiric activity in different phases of the pandemic. The reviewed findings suggest a pandemic-related enhancement of dream and nightmare frequency, emotional intensity, and distressing contents, modulated by modifications in restrictive measures and associated with diurnal experiences, emotional status, and sleep pattern. We highlight several methodological issues and a large heterogeneity in the present literature, limiting results' generalizability. However, we provide possible interpretations of the most consistent findings in light of the main theoretical frameworks about dreaming., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

A large body of evidence has documented the impact of the global COVID-19 outbreak - and especially the lockdown period - on sleep quality and quantity. Here, we present the first Italian longitudinal study on sleep and COVID-19 considering four different time points collected during lockdown (from 29 March 2020 to 3 May 2020) and a subsequent follow-up period (October 2020). We used an online survey to collect socio-demographic and COVID-19 related information. Subjects were also asked to complete a sleep diary at each time point of the study. Our longitudinal sample included 147 participants. Statistical comparison across time intervals showed remarkable changes in sleep patterns during and after the lockdown. In particular, during lockdown we observed longer sleep latency, less ease of falling asleep, a higher total bedtime, and a lower dream frequency. The week-by-week evaluation described relatively stable patterns in the observed measures during the lockdown period, except for dream frequency, affected by a rapid increase in the early phase of lockdown. Our findings are in line with the current literature. Furthermore, the prospective longitudinal investigation comprising several time points offered the possibility of (a) observing the temporal dynamics and the different entities of such changes over time, and (b) reducing the typical memory bias for these studies., (© 2021 The Authors. Journal of Sleep Research published by John Wiley & Sons Ltd on behalf of European Sleep Research Society.)

A growing body of evidence highlights that the COVID-19 pandemic affected oneiric activity. However, only a few studies have assessed the longitudinal changes in dream phenomenology during different phases of the pandemic, often focused on a limited number of dream variables. The aim of the present study was to provide an exhaustive assessment of dream features during total lockdown (TL) and a post-lockdown (PL) period characterized by eased restrictive measures in Italy. We performed a longitudinal study using a web-based survey to collect demographic, COVID-19 related, clinical, sleep, and dream data at TL and PL. Our final sample included 108 participants. The high frequency of poor sleep quality, anxiety, and depressive symptoms observed during TL remained stable at PL, while sleep latency (t = −4.09; p < 0.001) and PTSD-related disruptive nocturnal behaviors (t = −5.68; p < 0.001) exhibited a reduction at PL. A PL decrease in time spent with digital media was observed (t = −2.77; p = 0.007). We found a strong PL reduction in dream frequency (t = −5.49; p < 0.001), emotional load (t = −2.71; p = 0.008), vividness (t = −4.90; p < 0.001), bizarreness (t = −4.05; p < 0.001), length (t = −4.67; p < 0.001), and lucid dream frequency (t = −2.40; p = 0.018). Fear was the most frequently reported emotion in dreams at TL (26.9%) and PL (22.2%). Only the frequency of specific lockdown-related dream contents exhibited a reduction at PL. These findings highlight that the end of the home confinement had a strong impact on the oneiric activity, in the direction of reduced dream frequency, intensity, and lockdown-related contents. The co-occurrence of such changes with a decline in nocturnal PTSD-related symptoms, sleep latency, and time with digital media suggests an influence of post-traumatic stress levels, lifestyle modifications, and sleep pattern on dream changes during different phases of the pandemic. The stable prevalence of fear in dreams and the large frequency of poor sleep quality, depressive symptoms, and anxiety are probably related to the persistence of many negative consequences of the pandemic. Overall, these results are consistent with the continuity hypothesis of dreams.

Study Objectives: Individual circadian type is a ubiquitous trait defining sleep, with eveningness often associated with poorer sleep and mental health than morningness. However, it is unknown whether COVID-19 pandemic has differentially affected sleep and mental health depending on the circadian type. Here, the differences in sleep and mental health between circadian types are examined globally before and during the COVID-19 pandemic., Methods: The sample collected between May and August 2020 across 12 countries/regions consisted of 19 267 adults with information on their circadian type. Statistical analyses were performed by using Complex Sample procedures, stratified by country and weighted by the number of inhabitants in the country/area of interest and by the relative number of responders in that country/area., Results: Evening-types had poorer mental health, well-being, and quality of life or health than other circadian types during the pandemic. Sleep-wake schedules were delayed especially on working days, and evening-types reported an increase in sleep duration. Sleep problems increased in all circadian types, but especially among evening-types, moderated by financial suffering and confinement. Intermediate-types were less vulnerable to sleep changes, although morningness protected from most sleep problems. These findings were confirmed after adjusting for age, sex, duration of the confinement, or socio-economic status during the pandemic., Conclusions: These findings indicate an alarming increase in sleep and mental health problems, especially among evening-types as compared to other circadian types during the pandemic., (© Sleep Research Society 2021. Published by Oxford University Press on behalf of the Sleep Research Society.)

The Coronavirus 2019 pandemic strongly affected our sleep and dream activity. Many cross-sectional studies highlighted increased dream recall frequency, and revealed a great presence of pandemic-related oneiric contents. Here, we present the first prospective study carried out on an Italian sample. One-hundred subjects were requested to fill out a web-survey including socio-demographic information, and questionnaires collecting sleep and clinical measures during lockdown. A final sample of 90 subjects participated in the longitudinal protocol lasting 2 weeks: (a) the first week (April 28-May 4) of full lockdown; and (b) the second week (May 5-May 11) of easing of restrictions. Subjects were asked to record at home their dream experiences, and complete a sleep-dream diary each morning. Statistical comparisons showed that participants had higher numbers of awakenings, lower ease of falling asleep, higher dream recall and lucid dream frequency during lockdown than post-lockdown. Further, subjects reported more dreams, including "being in crowded places" during post-lockdown than lockdown. The poorer sleep quality during lockdown is quite consistent with previous findings. The relationship between traumatic events and dream recall frequency confirmed the idea of pandemic as "collective trauma". Also, we hypothesized that the greater presence of lucid dreams during confinement could reflect the attempt to cope with the waking pandemic-experiences. Finally, the presence of crowded places into dream scenarios during the second week of our protocol appears consistent with the continuity-hypothesis, as the possibility to access places frequented by other people could represent a relevant experience after a long period of confinement., (© 2021 The Authors. Journal of Sleep Research published by John Wiley & Sons Ltd on behalf of European Sleep Research Society.)

Objectives: Sleep is important for human health and well-being. No previous study has assessed whether the COVID-19 pandemic impacts sleep and daytime function across the globe., Methods: This large-scale international survey used a harmonised questionnaire. Fourteen countries participated during the period of May-August 2020. Sleep and daytime problems (poor sleep quality, sleep onset and maintenance problems, nightmares, hypnotic use, fatigue and excessive sleepiness) occurring 'before' and 'during' the pandemic were investigated. In total, 25 484 people participated and 22 151 (86.9%) responded to the key parameters and were included. Effects of COVID-19, confinement and financial suffering were considered. In the fully adjusted logistic regression models, results (weighted and stratified by country) were adjusted for gender, age, marital status, educational level, ethnicity, presence of sleep problems before COVID-19 and severity of the COVID-19 pandemic in each country at the time of the survey., Results: The responders were mostly women (64%) with a mean age 41.8 (SD 15.9) years (median 39, range 18-95). Altogether, 3.0% reported having had COVID-19; 42.2% reported having been in confinement; and 55.9% had suffered financially. All sleep and daytime problems worsened during the pandemic by about 10% or more. Also, some participants reported improvements in sleep and daytime function. For example, sleep quality worsened in about 20% of subjects and improved in about 5%. COVID-19 was particularly associated with poor sleep quality, early morning awakening and daytime sleepiness. Confinement was associated with poor sleep quality, problems falling asleep and decreased use of hypnotics. Financial suffering was associated with all sleep and daytime problems, including nightmares and fatigue, even in the fully adjusted logistic regression models., Conclusions: Sleep problems, fatigue and excessive sleepiness increased significantly worldwide during the first phase of the COVID-19 pandemic. Problems were associated with confinement and especially with financial suffering., Competing Interests: Competing interests: FC reports grants from Ontario Ministry of Health Innovation Grant and University Health Network Foundation, and personal fees from Masimo Inc and Takeda Pharma, outside the submitted work. In addition, University Health Network has a patent STOP-Bang questionnaire pending. YI reports personal fees and other from Astellas Pharma, personal fees from Eisai, other from Idorsia Pharmaceuticals Japan, grants from Koike Medical, personal fees from Otsuka Pharmaceutical and grants from Philips Japan outside the submitted work; DL reports grants from grants from Philips (Netherlands), Vanda (USA), Sanofi, Vitalaire International, Merck, and Janssen, Jazz and TYTHM outside the submitted work; KM reports personal fees from Eisai, Meiji Seika Pharma, Mochida, MSD, Otsuka Pharmaceutical and Yoshitomi Pharmaceutical, outside the submitted work; MP reports personal fees and other from Bioprojet, other from Jazz Pharmaceuticals, personal fees from UCB-Pharma, GSK, Takeda and Orion, personal fees and other from MSD and Umecrine, outside the submitted work. MP reports personal fees and other from Bioprojet, other from Jazz Pharmaceuticals, personal fees from UCB-Pharma, GSK, Takeda and Orion, personal fees and other from MSD and Umecrine, outside the submitted work; TP reports personal fees from Jazz Pharmaceuticals, personal fees from Bayer Healthcare, Neuwirth and Löwenstein Medical, outside the submitted work, and Shareholder of The Siestagroup GmbH, Advanced Sleep Research GmbH, Nukute; GP reports personal fees from UCB-Pharma, Jazz pharmaceuticals, Bioprojet,Idorsia, Takeda, outside the submitted work; Y-KW reports grants from Research Grant Council General Research Fund, grants from Health and Medical Research Fund, personal fees from Eisai Inc, personal fees from Eisai Co., Ltd, other from Lundbeck HK Limited, outside the submitted work., (© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Objective: The COVID-19 pandemic has strongly affected daily habits and psychological wellbeing, and many studies point to large modifications in several sleep and sleep-related domains. Nevertheless, pre-sleep arousal during the pandemic has been substantially overlooked. Since hyperarousal represents one of the main factors for the development and the perpetuation of chronic insomnia disorder, the assessment of variables associated with high levels of pre-sleep arousal during the pandemic is clinically relevant. The study aimed to assess the prevalence and predictors of perceived sleep quality and pre-sleep arousal in an Italian sample during the COVID-19 lockdown., Methods: We used an online survey to collect self-reported sociodemographic, environmental, clinical, sleep, and sleep-related data. Our final sample included 761 participants., Results: Beyond a high frequency of poor sleep quality, depressive and stress symptoms, our results show that almost half of the sample suffered from clinically relevant levels of at least one component (ie, cognitive, somatic) of pre-sleep arousal. Subjects with greater pre-sleep arousal exhibited poorer sleep quality. Also, sleep quality was strongly associated with somatic and cognitive pre-sleep arousal. Regarding the predictors of sleep and sleep-related measures, depressive and event-related stress symptoms were the main factors associated with both poor sleep quality and pre-sleep arousal components. Moreover, specific sociodemographic and environmental variables were uniquely related to sleep quality, cognitive or somatic pre-sleep arousal., Conclusions: These findings suggest that the assessment of specific sleep-related factors (ie, pre-sleep arousal), together with more global measures of sleep quality, may be crucial to depict the complex impact of the pandemic on sleep, and to help prevent and counteract the spread of insomnia symptoms., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Importance and Study Objective: The COVID-19 pandemic has produced unprecedented changes in social, work, and leisure activities, which all have had major impact on sleep and psychological well-being. This study documented the prevalence of clinical cases of insomnia, anxiety, and depression and selected risk factors (COVID-19, confinement, financial burden, social isolation) during the first wave of the pandemic in 13 countries throughout the world., Design and Participants: International, multi-center, harmonized survey of 22 330 adults (mean age = 41.9 years old, range 18-95; 65.6% women) from the general population in 13 countries and four continents. Participants were invited to complete a standardized web-based survey about sleep and psychological symptoms during the first wave of the COVID-19 pandemic from May to August 2020., Results: Clinical insomnia symptoms were reported by 36.7% (95% CI, 36.0-37.4) of respondents and 17.4% (95% CI, 16.9-17.9) met criteria for a probable insomnia disorder. There were 25.6% (95% CI, 25.0-26.2) with probable anxiety and 23.1% (95% CI, 22.5-23.6) with probable depression. Rates of insomnia symptoms (>40%) and insomnia disorder (>25%) were significantly higher in women, younger age groups, and in residents of Brazil, Canada, Norway, Poland, USA, and United Kingdom compared to residents from Asian countries (China and Japan, 8% for disorder and 22%-25% for symptoms) (all Ps < 0.01). Proportions of insomnia cases were significantly higher among participants who completed the survey earlier in the first wave of the pandemic relative to those who completed it later. Risks of insomnia were higher among participants who reported having had COVID-19, who reported greater financial burden, were in confinement for a period of four to five weeks, and living alone or with more than five people in same household. These associations remained significant after controlling for age, sex, and psychological symptoms., Conclusion and Relevance: Insomnia, anxiety, and depression were very prevalent during the first wave of the COVID-19 pandemic. Public health prevention programs are needed to prevent chronicity and reduce long-term adverse outcomes associated with chronic insomnia and mental health problems., (Copyright © 2021 Elsevier B.V. All rights reserved.)

COVID-19 has critically impacted the world. Recent works have found substantial changes in sleep and mental health during the COVID-19 pandemic. Dreams could give us crucial information about people's well-being, so here we have directly investigated the consequences of lockdown on the oneiric activity in a large Italian sample: 5,988 adults completed a web-survey during lockdown. We investigated sociodemographic and COVID-19-related information, sleep quality (by the Medical Outcomes Study-Sleep Scale), mental health (by the Depression, Anxiety, and Stress Scales), dream and nightmare frequency, and related emotional aspects (by the Mannheim Dream Questionnaire). Comparisons between our sample and a population-based sample revealed that Italians are having more frequent nightmares and dreams during the pandemic. A multiple logistic regression model showed the predictors of high dream recall (young age, female gender, not having children, sleep duration) and high nightmare frequency (young age, female gender, modification of napping, sleep duration, intrasleep wakefulness, sleep problem index, anxiety, depression). Moreover, we found higher emotional features of dream activity in workers who have stopped working, in people who have relatives/friends infected by or who have died from COVID-19 and in subjects who have changed their sleep habits. Our findings point to the fact that the predictors of high dream recall and nightmares are consistent with the continuity between sleep mentation and daily experiences. According to the arousal-retrieval model, we found that poor sleep predicts a high nightmare frequency. We suggest monitoring dream changes during the epidemic, and also considering the implications for clinical treatment and prevention of mental and sleep disorders., (© 2021 European Sleep Research Society.)

A growing body of evidence consistently describes the side-effects of coronavirus disease 2019 lockdown on mental health and sleep quality. We conducted a longitudinal web-based survey of 217 Italian participants at two time points: lockdown and subsequent follow-up. To thoroughly investigate lockdown-related changes in sleep quality, we first evaluated variations in overall sleep quality assessed by the Pittsburgh Sleep Quality Index. We then examined sleep changes in specific components of sleep quality. Results revealed a clear dissociation of sleep effects, as a function of the specific domain considered, with longer sleep latency, worse sleep efficiency, and massive sleep medication use during forced confinement. On the other hand, we simultaneously observed an increased sleep duration and better daytime functioning. Our present findings highlight the importance of an accurate examination of sleep quality during lockdown, as the effects were not uniform across populations and different sleep domains., (© 2021 The Authors. Journal of Sleep Research published by John Wiley & Sons Ltd on behalf of European Sleep Research Society.)

Purpose: Obstructive sleep apnea (OSA) may increase the risk of severe COVID-19; however, the level of potential modulation has not yet been established. The objective of the study was to determine the association between high risk of OSA, comorbidities, and increased risk for COVID-19, hospitalization, and intensive care unit (ICU) treatment., Methods: We conducted a cross-sectional population-based web survey in adults in 14 countries/regions. The survey included sociodemographic variables and comorbidities. Participants were asked questions about COVID-19, hospitalization, and ICU treatment. Standardized questionnaire (STOP questionnaire for high risk of OSA) was included. Multivariable logistic regression was conducted adjusting for various factors., Results: Out of 26,539 respondents, 20,598 (35.4% male) completed the survey. Mean age and BMI of participants were 41.5 ± 16.0 years and 24.0 ± 5.0 kg/m 2 , respectively. The prevalence of physician-diagnosed OSA was 4.1% and high risk of OSA was 9.5%. We found that high risk of OSA (adjusted odds ratio (aOR) 1.72, 95% confidence interval (CI): 1.20, 2.47) and diabetes (aOR 2.07, 95% CI: 1.23, 3.48) were associated with reporting of a COVID-19 diagnosis. High risk for OSA (aOR 2.11, 95% CI: 1.10-4.01), being male (aOR: 2.82, 95% CI: 1.55-5.12), having diabetes (aOR: 3.93, 95% CI: 1.70-9.12), and having depression (aOR: 2.33, 95% CI: 1.15-4.77) were associated with increased risk of hospitalization or ICU treatment., Conclusions: Participants at high risk of OSA had increased odds of having COVID-19 and were two times more likely to be hospitalized or treated in ICU.

Objective: The lockdown due to COVID-19 pandemic had a strong impact on daily habits, emotional experience, mental health and sleep. A large body of evidence suggests that dreams are affected by both waking experiences and sleep pattern. In this view, the lockdown should have induced intense modifications in dreaming activity. The aim of the study was to assess dream features during the lockdown in Italy., Methods: We used an online survey to collect self-reported demographic, clinical, sleep and dream data. Our sample included 1091 participants., Results: Results point to an increased dream frequency, emotional load, vividness, bizarreness and length during the lockdown, compared to a pre-lockdown period. Higher dream frequency and specific qualitative features were found in females and subjects with poor sleep quality, nocturnal disruptive behaviours and depressive symptoms. Most of the dream features assessed during the lockdown were predicted by age, gender, depressive symptoms, presence/absence of other people at home, and territorial area. A specific focus on sleep features revealed that sleep duration and several sleep quality indexes were the best predictors of dream variables. During the lockdown, dreams were also characterized by increased negative emotions, which were particularly frequent in females, younger adults, and participants with poor sleep quality, nocturnal disruptive behaviours, anxiety and depressive symptoms., Conclusions: Our results confirm the hypothesis of a strong influence of the pandemic on dreaming, supporting both the hypothesis of continuity between wake and sleep mental processes and the view of a crucial influence of sleep quality and duration on dreaming activity., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Brigitte Holzinger,1,2 Franziska Nierwetberg,1 Frances Chung,3 Courtney J Bolstad,4 Bjørn Bjorvatn,5 Ngan Yin Chan,6 Yves Dauvilliers,7 Colin A Espie,8 Fang Han,9 Yuichi Inoue,10 Damien Leger,11 Tainá Macêdo,12 Kentaro Matsui,13,14 Ilona Merikanto,15,16 Charles M Morin,17 Sérgio A Mota-Rolim,18 Markku Partinen,19 Giuseppe Plazzi,20,21 Thomas Penzel,22 Mariusz Sieminski,23 Yun Kwok Wing,6 Serena Scarpelli,24 Michael R Nadorff,4,25 Luigi De Gennaro24,26 1Institute for Consciousness and Dream Research, Vienna, Austria; 2Medical University Vienna, Postgraduate Master ULG Sleep Coaching, Vienna, Austria; 3Department of Anesthesiology and Pain Medicine, University Health Network, University of Toronto, Toronto, ON, Canada; 4Mississippi State University, Mississippi State, MS, USA; 5Department of Global Public Health and Primary Care, University of Bergen and Norwegian Competence Center for Sleep Disorders, Haukeland University Hospital, Bergen, Norway; 6Li Chiu Kong Family Sleep Assessment Unit, Department of Psychiatry, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong, Special Administrative Region, People’s Republic of China; 7Sleep-Wake Disorders Unit, Department of Neurology, Gui-de-Chauliac Hospital, CHU Montpellier, INM, Univ Montpellier, INSERM, Montpellier, France; 8Sir Jules Thorn Sleep & Circadian Neuroscience Institute (SCNi), University of Oxford, Oxford, UK; 9Department of Pulmonary and Critical Care Medicine, Peking University People’s Hospital, Beijing, People’s Republic of China; 10Tokyo Medical University, Tokyo, Japan; 11Université de Paris, APHP, Hôtel-Dieu, Centre du Sommeil et de la Vigilance, Paris, France; 12Department of Psychology, Federal University of Rio Grande do Norte, Natal, Brazil; 13Department of Laboratory Medicine, National Center Hospital, National Center of Neurology and Psychiatry, Kodaira, Japan; 14Department of Psychiatry, Tokyo Women’s Medical University, Tokyo, Japan; 15SleepWell Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland; 16Department of Public Health and Welfare, Finnish Institute for Health and Welfare, Helsinki, Finland; 17École de Psychologie, Centre d’étude des troubles du sommeil, Centre de recherche CERVO/Brain Research Center, Université Laval, Québec, QC, Canada; 18Brain Institute, Physiology and Behavior Department, and Onofre Lopes University Hospital - Federal University of Rio Grande do Norte, Natal, Brazil; 19Helsinki Sleep Clinic, Terveystalo Healthcare, and Department of Neurosciences, Clinicum, University of Helsinki, Helsinki, Finland; 20IRCCS, Istituto delle Scienze Neurologiche di Bologna, Bologna, Italy; 21Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy; 22Sleep Medicine Center, Charité Universitätsmedizin Berlin, Berlin, Germany; 23Department of Emergency Medicine, Medical University of Gdansk, Gdansk, Poland; 24Department of Psychology, Sapienza University of Rome, Rome, Italy; 25Department of Psychiatry and Behavioral Sciences, Baylor College of Medicine, Houston, TX, USA; 26IRCCS Fondazione Santa Lucia, Rome, ItalyCorrespondence: Brigitte Holzinger, Tel +43 699 101 99 042, Email brigitte.holzinger@meduniwien.ac.atPurpose: The COVID-19 pandemic affects mental health and sleep, resulting in frequent nightmares. Therefore, identifying factors associated with nightmare frequency is important, as it can indicate mental health issues. The study aimed to investigate increases in nightmare frequency comparing the pre-pandemic and pandemic period, and identify its risk factors. Further, the mediating role of post-traumatic stress disorder symptoms between the pandemic and nightmares is explored.Patients and Methods: For this cross-sectional survey data were obtained via self-rating online survey (ICOSS: details in Partinen et al, 2021), which was open to anyone older than 18 years. The final volunteer sample consisted of 15,292 participants, divided according to their nightmare frequency (high: ≥ 1– 2 nights/week; low: < 1– 2 nights/week). A total of 9100 participants were excluded if answers on variables of interest were missing or receiving rewards for participation. Chi-square tests identified changes of nightmare frequency. Predictors of high nightmare frequency were assessed using logistic regression and presented as Odds Ratios. Post-hoc mediation models were used to investigate the role of post-traumatic stress symptoms (PTSS).Results: The mean age was 41.63 (SD=16.55) with 64.05% females. High nightmare frequency increased significantly from 13.24% to 22.35% during the pandemic. Factors associated with it included self-reported PTSS (OR=2.11), other mental disorders and various sleep disorders or problems. Financial burden due to the pandemic, confinement, having had COVID-19, and work situation during the pandemic were associated with nightmare frequency, those relations were partly mediated through PTSS.Conclusion: Our results display the pandemic influence on nightmare frequency, which in turn connects to multiple mental health and sleep factors. These relations were partly mediated through PTSS. The COVID-19 pandemic appears to have caused traumatization of a substantial proportion of society. Health care workers should consider nightmares in their screening routines, as it might indicate PTSS and/or other mental and sleep disorders.Keywords: COVID-19, nightmares, mental health, sleep, post-traumatic stress disorder, collective trauma