Subjective and Objective Sleep Measures in Patients With Insomnia With and Without Depression

INTRODUCTION: Objectively measured sleep duration often diverges from the subjectively perceived sleep duration in patients with insomnia. Although depression is known to affect sleep, little is known about its influence on the discrepancy between subjective and objective sleep measures, which we sought to clarify in this study. METHODS: We analyzed medical records from 229 patients with insomnia, including anamnestic data, Pittsburgh Sleep Quality Index (PSQI) and Beck Depression Inventory (BDI) scores, and polysomnography and actigraphy measurements. Patients were compared according to their anamnesis of depressive disorder and BDI scores. Group differences were evaluated using Wilcoxon rank-sum tests and multivariate linear regression with log-transformed outcomes to control for relevant confounders. RESULTS: Patients with insomnia (mean PSQI score 12.4) and comorbid depression (as a trait) showed significantly higher sleep-onset latency, lower sleep efficiency, and longer total sleep time, as assessed by actimetry. Patients with insomnia and relevant depressive symptoms (BDI score ≥14 points) did not differ from those without relevant depression in objective sleep measurements. However, they presented significantly higher scores on subjective measurements of overall sleep quality, sleep latency, sleep disturbances, and daytime disturbances. CONCLUSIONS: In patients with insomnia, current depressive symptoms have an impact only on the subjective perception of sleep, whereas comorbid depressive disorder also influences objective sleep measurements. A clearer understanding of the discrepancy between subjective and objective sleep measures across different patient cohorts will enhance personalized treatment in patients with insomnia.