Abstract
BACKGROUND: Many patients with bipolar disorder (BD) experience sleep problems. Sleep abnormalities are associated with immune dysfunction, which may be reflected by hematological indices. Purpose: This study aimed to investigate the association between sleep quality and the neutrophil-to-lymphocyte ratio (NLR) and the platelet-to-lymphocyte ratio (PLR) in patients with BD. METHODS: This cross-sectional study was performed at Imam Hossein Hospital, Tehran, Iran, from March to September 2023. Hospitalized patients newly diagnosed with BD were interviewed to complete questionnaires. Sleep quality and manic and depressive symptoms of the participants were assessed using the Pittsburg Sleep Quality Index (PSQI), the Young Mania Rating Scale (YMRS), and the Hamilton Depression Rating Scale (HDRS), respectively. Furthermore, blood samples were taken from each patient to investigate hematological indices. Continuous and categorical variables were compared between groups using an independent-sample t test and chi-square/Fisher's exact tests, respectively. The Poisson regression model was also used to investigate predictors of the PSQI score. RESULTS: Of 305 patients included in the study, 78.7% and 21.3% were experiencing manic and depressive episodes, and 90.20% had poor sleep quality. The prevalence of poor sleep quality was significantly higher in depressed patients than in manic patients (100% vs. 87.5%; P = 0.003). Depressed patients had significantly higher platelet counts (mean difference [MD], 34.09 [95% CI, 9.35-58.83]; P = 0.007) and PLR (MD, 38.14 [95%CI, 10.25-66.02]; P = 0.008) and lower lymphocyte counts (MD, 266.04 [95% CI, [14.41-517.67]; P = 0.038) compared with manic patients. The Poisson regression model with adjustment revealed that men (risk ratio [RR], 1.113; P = 0.025), those with lower educational levels (RR, 1.164; P = 0.001), and those with higher HDRS scores (RR, 1.370; P < 0.001) had significantly deteriorated sleep quality. CONCLUSION: Most bipolar patients have poor sleep quality, particularly those with depressive episodes. Depressed patients had significantly higher platelet counts and PLR. Also, depressed patients with male sex, lower educational levels, and more severe depressive symptoms had poorer sleep quality.