The Prevalence and Impact of Obstructive Sleep Apnoea and Periodic Limb Movements in Sleep in Adult Parasomnias

Background: Parasomnias are abnormal behaviours in sleep. Disorders that can cause microarousals, such as obstructive sleep apnoea (OSA) and periodic limb movements in sleep (PLMS) are often considered to trigger parasomnias. However, the prevalence and impact of OSA, and its specific clinical phenotypes, such as REM-related OSA (ROSA) and positional OSA (POSA), as well as PLMS in parasomnias are not fully explored. Methods: We analysed the polysomnography reports of 155 patients who were referred to our tertiary service with symptoms of parasomnia. The prevalence of OSA, ROSA, POSA, and PLMS, as well as their severity indices were correlated with the prevalence of specific parasomnias using logistic regression. Results: The prevalence of OSA and PLMS was 48% and 23%, respectively. Whilst OSA and PLMS were inversely related to NREM parasomnias, PLMS was directly related to RBD (p < 0.05). Moreover, there was a significant inverse correlation between the severity of PLMS and the prevalence of NREM parasomnias (β = −0.12, p = 0.03) and a direct correlation with RBD (β = 0.02, p = 0.04). However, following adjustments for age, BMI, and gender, only the inverse relationships between OSA and sleep terrors as well as POSA and sleep-related eating disorder remained significant. Conclusions: The prevalence of OSA and PLMS is high among patients with parasomnia. Due to the exploratory nature of the study, conclusions on the associations need to be validated in interventional trials.