Sleep in Parkinson's disease. The role of depression and anxiety.

Sleep disorders are frequent and well documented in patients with Parkinson's disease (PD). The effect of depression and anxiety on sleep in PD patients has not been carefully studied however, despite the fact that both depression and anxiety are common in PD and well known to affect sleep in patients without PD. In this questionnaire study, sleep, anxiety, and depression were evaluated in 99 patients with PD and 47 control subjects. PD patients had significantly higher scores on a variety of sleep variables as well as on measures of anxiety and depression. While anxiety and depression were correlated with some sleep measures, neither contributed significantly to overall variance in sleep quality. The effect on sleep variables was dominated by on-off symptom phenomena, levodopa dose, and age.