Diurnal fluctuations of local field potentials follow sleep-wake behavior in Parkinson's disease

Abstract Background: Sleep disturbances are among the most common non-motor symptoms of Parkinson’s disease (PD). Deep brain stimulation (DBS) of the subthalamic nucleus (STN) reduces local field potential (LFP) activity in the STN, particularly in the beta frequency range (13 – 30 Hz). Although well-characterized in the short term, little is known about how beta frequency oscillations change chronically, across the sleep-wake cycle. Better understanding of these pathological signals in sleep may permit optimization of stimulation to improve sleep in PD. Objectives: Here, we sought to characterize LFPs over several days and nights while patients remained in the home setting. Methods: LFPs were recorded from the subthalamic nucleus in 13 PD subjects (18 hemispheres) over an average of 14.7 ± 4.2 days. Fluctuations in LFP activity were characterized by arousal state, as determined by actigraphy. Results: Beta frequency LFPs showed a clear and consistent diurnal pattern. In all subjects, beta power was higher during wakefulness than during sleep, with little overlap in the magnitude of beta power between these two activity states. LFP snapshots obtained across a broad frequency range at subject-indicated going-to-bed and waking-up times showed significant differences in power across multiple canonical frequency bands, though these differences were not significant at the group level. Conclusions: Beta frequency LFPs fluctuate in a clear and consistent manner that is closely linked to time of day and to activity state. These fluctuations can be detected in the home setting using commercially available devices, including in patients who have been treated with deep brain stimulation for several years.