Background: and Purpose Epidemiological data on narcolepsy are rare in South Korea.We aimed to provide an overview of the burden of narcolepsy and its temporal trend in South Korea. Methods: Patients with narcolepsy were identified by their registration in the Rare and Intractable Disease (RID) register and the Health Insurance Review and Assessment database.Individuals registered in the RID program with the code V234 were considered as having ‘definite narcolepsy’, while those who claimed health insurance with G47.4 as the primary diagnostic code were considered as having ‘probable narcolepsy’. We estimated the annual prevalence, incidence, and medical costs of narcolepsy between 2010 and 2019. Results: The prevalence of definite narcolepsy was 8.4/100,000 in 2019, peaking at 32.0/100,000 in those aged 15–19 years. The prevalence was higher in males, with a relative risk of 1.72. The prevalence has increased over the past 6 years, with an average annual growth rate (AAGR) of 12.2%. The prevalence of probable narcolepsy was 10.7/100,000 in 2019. The incidence of definite narcolepsy increased up to 1.3/100,000 in 2019 with an AAGR of 7.1%. Annual medical expenditure for definite narcolepsy gradually increased up to 4.1 billion KRW in 2019, with a compound annual growth rate of 11.9%. Conclusions This study has provided the first nationwide estimates for narcolepsy in South Korea. The prevalence of diagnosed narcolepsy in South Korea was at the low end of the range of narcolepsy prevalence rates reported for other countries. However, the prevalence and incidence have been steadily increasing over the past decade.

Background: The coronavirus disease 2019 (COVID-19) pandemic has led to heightened mood disturbances linked to increased electronic device use at bedtime (EUB). General anxiety may contribute to an increased likelihood of experiencing nocebo responses, which have been reported to be associated with COVID-19 vaccine-related adverse events (CAEs).However, no related studies have been conducted to examine this association to date. Methods: We executed a nationwide cross-sectional study to explore these correlations during the pandemic. Using data from the 2022 National Sleep Survey of South Korea, we analyzed the sleep health of 4,000 adults aged 20–69 years between January and February 2022. Shift workers and those with severe sleep disorders were excluded. Participants with EUB more than four days a week were labeled as high frequency EUB, and those reporting CAEs after both vaccine doses were marked as having a presence of CAEs. The survey also included details about anthropometric data, socioeconomic status, and sleep status. Results: Of the 3,702 participants, 92.6% had received two or more vaccine doses, with 41.2% experiencing CAEs. Furthermore, 73.7% had a high EUB frequency. Factors associated with CAE reporting included younger age, female sex, and high EUB frequency, while heavy alcohol use was found to be less likely to be associated with CAE reporting. Notably, a high EUB frequency was significantly associated with reported CAEs (odds ratio, 1.223; 95% confidence interval, 1.028–1.455; P = 0.023). Conclusion A nationwide online survey conducted in South Korea during the pandemic found that individuals who engaged in the relatively frequent use of electronic devices during bedtime had worse sleep quality and increased COVID-19-related adverse events compared with those using these devices less frequently. These findings have the potential to enhance our understanding of the impact of the use of electronic devices at bedtime on health.