The bidirectional longitudinal relationship between insomnia, depression and anxiety in patients with early-stage, medication-naïve Parkinson's disease

Symptoms of anxiety and depression may constitute a risk factor for insomnia in PD. The relationship between insomnia and anxiety is bidirectional, which suggests that both anxiety and sleep disorders can start a negative spiral in PD patients, where one enhances the other. Independent clinical attention for these symptoms in PD patients is therefore warranted.