HCRT and major depressive disorder: Among the three groups, we observed a significant difference (K-W: P < 0.001, Figure 1A), in that plasma hypocretin-1 levels were significantly higher in MDD [59.04 (35.78–80.12) pg/ml] and BD [65.50 (58.46–74.57) pg/ml] patients than in controls [49.25 (28.51–80.40) pg/ml].