Prevalence Rates of Frequent Dream Recall and Nightmares by Age, Gender and Sleep Duration in 16 Countries.

The present study aimed to describe the prevalence rates of frequent (i.e., at least weekly) dream recall and nightmares with consideration for differences in age, gender and sleep duration in 16 countries using equivalent assessment methods. The study sample included 15,854 participants (69.9% women) aged 18-99 years (M = 42.39, SD = 16.43) collected by the International COVID-19 Sleep Study collaboration, which used a unified online survey to collect data from May to November 2021 across 16 countries. Participants provided demographic information as well as self-reported estimates of their dream recall and nightmare frequency and sleep duration in 2021 and retrospectively for 2019. Frequent dream recall occurred in 54.0% of participants in 2021 and 51.1% in 2019. Frequent nightmares were reported by 11.0% of participants in 2021 and 6.9% in 2019. Ad hoc regression models found dream recall and sleep duration to have a linear relation, whereas nightmare frequency demonstrated a quadratic relation to sleep duration. Frequent dream recall and nightmare prevalence rates are reported for each of the 16 study countries by age, gender and sleep duration. This is the first multi-continent study to estimate frequent dream recall and nightmare prevalence, which both provides updated prevalence rates during the COVID-19 pandemic as well as extends existing knowledge to previously never studied countries.