Fig. 2

Distribution of Beck depression inventory (BDI) scores according to sleep quality in patients with chronic migraine. Box plots demonstrate a comparison between patients with poor (PSQI ≥ 6) and good sleep quality (PSQI < 6). The horizontal line within each box represents the median, boxes indicate the interquartile range (IQR), and whiskers extend to the most extreme data points within 1.5 times the IQR. Outliers are indicated by circles (values ​​> 1.5 times the IQR)