Figure 1.

Lower self‐reported total sleep time (TST) on the Pittsburgh Sleep Quality Index was associated with depression severity on the Beck Depression Inventory, 2nd ed. (BDI‐II) among patients with Parkinson's disease (PD) but not among matched controls (MC), r _s(47) = −0.47, p = .001; r _s(47) = −0.04, p = .769, respectively. Fisher's test showed that the correlation between TST and adjusted BDI‐II score was stronger in the PD group than the MC group, Z = −2.21, p = .027. Adjusted BDI‐II total scores did not include item 16 (i.e., sleep changes). Closed circles and black line represent patients with PD; open circles and dotted line represent MC