Exploration of Insomnia With Excessive Daytime Sleepiness From Clinical and Polysomnographic Perspectives

Objectives: Insomnia is a disorder that involves poor sleep quality at nighttime and various symptoms in the daytime. Although it is known to increase cardiovascular risk as well as psychiatric comorbidities such as depression and anxiety, less attention has been paid to daytime sleepiness in patients with insomnia. This study aimed to investigate clinical and polysomnographic characteristics and identify factors influencing excessive daytime sleepiness in patients with insomnia.Methods: Between 2014 and 2022, 1,241 patients with insomnia as the primary symptom who underwent polysomnography were included in the study. Patients with an Epworth sleepiness scale ≥10 were classified as having insomnia accompanied by daytime sleepiness, and sleep-related questionnaire responses and polysomnography findings were utilized for analysis.Results: A total of 327 patients (26.3%) had daytime sleepiness, and a higher prevalence was observed in younger and male individuals. Poor sleep quality, severe depression, and insomnia were identified through the questionnaire. Polysomnography showed longer total sleep times, a higher proportion of stage N3 sleep, and higher sleep efficiency. The variables related to the Epworth sleepiness scale identified in multiple regression analysis were age, the Korean Beck Depression Inventory-II, sleep latency, and the apnea-hypopnea index on polysomnography.Conclusions: Insomnia with excessive daytime sleepiness was more affected by depression than indicated by polysomnography findings. The pathophysiology is presumed to be related to sleep misperception, and further studies are needed to elucidate the discrepancy between excessive daytime sleepiness and polysomnography findings.