Summary 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.

In order to control the rapid spread of the COVID-19 pandemic, Austria was put under national lockdown beginning on March 13, 2020, forcing its inhabitants to live in home confinement. The aim of this study was to measure the impact of the lockdown on sleep and dream behavior in Austrian citizens. 77 participants (50 women, 40.88 years, = 13.72) filled in an online questionnaire during the lockdown between April and May 2020. Sleep quality, sleep quantity, daytime sleepiness, and nightmare frequency were assessed and analyzed in relation to gender, burnout risk, perfectionism and chronotype. Results demonstrated higher subjective sleep quality during lockdown, especially in women. Daytime sleepiness was significantly lower during the lockdown period while sleep duration did not change. Results suggest that sleep issues are less prominent during the COVID-19 lockdown but point to the importance of prevention and treatment of sleep disorders aside from the pandemic. Findings indicate the need for more flexibility in social time structures to relieve those managing tasks from multiple areas of interests such as working mothers. Generalization of results is limited due to small sample size, self-selection bias, and purely subjective measures.

The pandemic caused by the coronavirus disease 2019 (COVID-19) had a huge impact on public mental health. This was also reflected in dreams. Not only did people start to remember more dreams, but dream content changed as themes like sickness, confinement, and—in the English-speaking world—even bugs began to dominate. This also led to an increase in nightmare frequency. There are various factors that contributed to this change in the dream landscape. Some people have started to sleep more and hereby spend more time in REM sleep, which is known to increase dream recall and further lead to bizarre and vivid dreams. On the other hand, stress and poor mental health had an impact on sleep, and sleep quality thus dropped in many individuals. Poor sleep quality can also lead to an increase in dream recall. Dreams are known to regulate mood, so the rise in dreams and the change in dream content could also reflect a reaction to the overall rise in stress and decline in mental health. Recent studies have shown that as the pandemic progresses, further changes in mental health, dream recall, and dream content arise, but data are still scarce. Further research could help understand the impact the pandemic still has on mental health and dreams, and how this impact is changing over the course of the pandemic.

Purpose 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.

Validated instruments for the analysis of dream contents are still scarce. Therefore, the aim of this study was to validate the Dreamland Questionnaire (DL-Q) by comparing its results to those of the Hall and van de Castle Coding System (HVDC). Twenty-two participants voluntarily filled in a written dream report as well as our DL-Q questionnaire, in total 30 dreams were collected with both measures. Written reports were analyzed with the HVDC and results of the two instruments were compared using Pearson correlations. Results showed that correlations were high for dominant characters, pleasantness of dream content, and body-related experiences. However, some DL-Q items showed low correlations and others could not be compared directly, as the HVDC did not include the same set of items. The DL-Q showed satisfactory validity and reliability as a measure of dream criteria and may serve as an effective tool for diagnosis and evaluation and facilitate future clinical and research studies. Nevertheless, some items could not be compared as part of this study and should be validated in future investigations.