4.5. Statistical Analysis

Statistical analysis was performed with SPSS 28.0 (IBM, Armonk, NY, USA). The distribution was evaluated using the Shapiro–Wilk test. Variables with normal distribution were compared using independent Student t-tests, and non-normally distributed parameters by Mann–Whitney U test. Nominal variables were analyzed using chi-square tests. Correlations were examined by Spearman’s rank correlation test. Multivariable linear regression with a stepwise procedure was applied to investigate the predictive factors of the ISI score. Logistic regression models were created to search for predictive factors of clinically significant insomnia (ISI ≥ 15) and estimated odds ratio (OR) with 95% confidence intervals (CI). The level of statistical significance was set at p < 0.05.