Sleep disturbances in untreated Parkinson's disease

Sleep abnormalities are frequently found in Parkinson's disease (PD). However, it is unclear if they are present from the initial stages of PD. We thus aimed to assess sleep disturbances in newly diagnosed PD patients. We investigated 20 untreated PD patients using the Epworth Sleepiness Scale (ESS), the Pittsburgh Sleep Quality Index (PSQI) and the PD Sleep Scale (PDSS). Video-polysomnography and multiple sleep latency test (MSLT) were performed in 15 patients and 15 healthy controls. The ESS score was abnormally high in one patient, while short MSLT times were found in three other patients. The PSQI was higher (p < 0.05) and the PDSS lower (p < 0.001) in patients compared with controls. Video-polysomnography demonstrated a higher percentage of rapid eye movement sleep without atonia (RWA) in patients compared with controls (mean 28 vs. 2.9%, p < 0.001), whereas only one patient had clinically manifested rapid eye movement sleep behavior disorder (RBD). Interestingly, the occurrence of RWA correlated with the motor score (ρ = 0.65, p < 0.05). This study demonstrates that sleep disturbances emerge, in a proportion of patients, from the early stages of PD. RWA is a common finding while RBD is rarely present in early untreated PD.