Category: Sleep / Wake Disorders
Current diagnostic criteria of insomnia largely depend on subjective symptoms which include sleep onset latency or difficulty maintaining sleep. However, individuals with insomnia tend to underestimate the amount of their actual sleep, and their subjective report commonly contradicts sleep duration determined by an objective measure such as polysomnography (PSG) (Fernandez-Mendoza et al., 2015). Recent findings indicate that insomnia with objective normal sleep duration closely associates with psychological processes (e.g., sleep misperception), whereas insomnia with short sleep duration exhibits stronger biological basis (e.g., hyperarousal) (Vgontzas et al., 2012). It is also suggested that mental health outcomes of insomnia may be significantly moderated by objectively measured sleep duration (Vgontzas, Fernandez-Mondoza, Liao & Bixler, 2013), but there is a lack of replication in ethnically diverse populations. Therefore, the current study aimed to further examine the association between insomnia, objective sleep duration, and psychological outcomes in a representative Korean adult sample, namely the Korean Genome and Epidemiology Study (KoGES).
A total of 2679 community-dwelling middle-aged and older adults (mean age 59.1 ± 7.1, 50.7% female) were categorized into insomnia groups (Insomnia/Control) based on the presence of self-reported difficulty initiating sleep, difficulty maintaining sleep, or early morning awakening during the past one month. They were further grouped into objective sleep duration groups based on the PSG-measured total sleep time (short sleep ( < 6 h) and normal sleep duration (≥6 h)). Depression symptoms and suicidal ideation were measured by the Beck Depression Inventory (BDI), and daytime sleepiness was measured by the Epworth Sleepiness Scale (ESS).
Insomnia was present in 16.2% of the study sample (N=437). Results from multivariate analysis of covariance suggested that Insomnia was associated with higher BDI score compared to Control after adjusting for age, sex, body-mass index, education, hypertension, diabetes, smoking, alcohol consumption, and sleep apnea (F=112.6, p= < .0001). Insomnia was also significantly associated with greater odds or having suiciding ideation (odds ratio (OR) = 2.3, 95% confidence interval (CI)=1.8-2.9). Among individuals with Insomnia, 58.4% (n=255) had objective normal sleep duration. Dividing the groups further by the objective sleep duration yielded a significant difference in BDI across the Insomnia x objective sleep duration groups (F=38.12, p= < .0001), and post-hoc analyses revealed that Insomnia with normal sleep duration (but not Insomnia with short sleep) was had significantly higher BDI scores compared to Control groups. Suicidal ideation was not different by objective sleep duration in Insomnia. There was no difference in the ESS across the Insomnia and objective sleep duration groups. Our results indicated that depression symptoms may manifest differently in insomnia groups by the presence of objective normal sleep duration. Phenotyping insomnia with objective sleep measures, such as PSG, may strengthen the current diagnostic and treatment systems.
Hyun Kim– PhD Student, Boston University, Boston, Massachusetts
Robert Thomas– Assistant Professor of Medicine, Beth Israel Deaconess Medical Center/ Harvard Medical School
Chang-Ho Yun– Seoul National University Bundang Hospital
Seungku Lee– Korea University Ansan Hospital
Michael Lyons– Professor, Boston University
Chol Shin– Korea University Ansan Hospital
Assistant Professor of Medicine
Beth Israel Deaconess Medical Center/ Harvard Medical School