Nightmares share genetic risk factors with sleep and psychiatric traits

Nightmares are vivid, negative dreams that awaken the dreamer. While occasional nightmares are common, frequent ones often indicate underlying emotional regulation problems. A genome-wide association study of 45,255 individuals found no single genetic variants linked to nightmare frequency, but estimated heritability at 5%. Genetic correlation analysis revealed strong correlations between nightmares and anxiety, depressive disorders, posttraumatic stress disorder, and the personality trait neuroticism. Mendelian randomization suggested that insomnia may causally increase the likelihood of frequent nightmares. These findings indicate that nightmares share genetic factors with psychiatric conditions and that insomnia may heighten susceptibility to nightmares, highlighting the need for systematic nightmare assessment in clinical settings.

Study at a glance

Abstract

Nightmares are vivid, extended, and emotionally negative or negative dreams that awaken the dreamer. While sporadic nightmares and bad dreams are common and generally harmless, frequent nightmares often reflect underlying pathologies of emotional regulation. Indeed, insomnia, depression, anxiety, or alcohol use have been associated with nightmares in epidemiological and clinical studies. However, the connection between nightmares and their comorbidities are poorly understood. Our goal was to examine the genetic risk factors for nightmares and estimate correlation or causality between nightmares and comorbidities. We performed a genome-wide association study (GWAS) in 45,255 individuals using a questionnaire-based assessment on the frequency of nightmares during the past month and genome-wide genotyping data. While the GWAS did not reveal individual risk variants, heritability was estimated at 5%. In addition, the genetic correlation analysis showed a robust correlation (rg > 0.4) of nightmares with anxiety (rg = 0.671, p = 7.507e-06), depressive (rg = 0.562, p = 1.282e-07) and posttraumatic stress disorders (rg = 0.4083, p = 0.0152), and personality trait neuroticism (rg = 0.667, p = 4.516e-07). Furthermore, Mendelian randomization suggested causality from insomnia to nightmares (beta = 0.027, p = 0.0002). Our findings suggest that nightmares share genetic background with psychiatric traits and that insomnia may increase an individual's liability to experience frequent nightmares. Given the significant correlations with psychiatric and psychological traits, it is essential to grow awareness of how nightmares affect health and disease and systematically collect information about nightmares, especially from clinical samples and larger cohorts.