Effects of light therapy on sleep and anxiety in Parkinson's disease: A pilot trial.
Effects of light therapy on sleep and anxiety in Parkinson's disease: A pilot trial.
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Original abstract
BACKGROUND: Light therapy (LT) may improve sleep and affective disorders in Parkinson's disease (PD), but effects of different intensities and underlying mechanisms remain unclear. METHODS: Thirty-three patients with PD were randomized to receive either 1 month of bright LT (BLT) at 10000 lx or dim LT (DLT) at 200 lx, separated by a 1-month washout period, in a crossover fashion. All patients completed clinical assessments, polysomnography (PSG) and resting-state electroencephalogram (EEG) at baseline and after each intervention period. Functional connectivity was assessed using weighted Phase Lag Index (wPLI). RESULTS: Both BLT and DLT significantly reduced Pittsburgh Sleep Quality Index (PSQI). BLT showed a greater reduction in Epworth Sleepiness Scale (ESS) (P = 0.009), whereas DLT showed a greater reduction in Hamilton Anxiety Rating Scale (HAMA) (P = 0.030). In within-treatment comparisons, BLT was associated with increased slow wave energy (P = 0.001) and theta-band wPLI between specific visual network(VN) pairs, while DLT was associated with increased slow wave sleep proportion (P = 0.006) and alpha-band mean default mode network (DMN) wPLI. However, between-treatment comparisons revealed no significant differences in any PSG or EEG outcomes. CONCLUSIONS: BLT showed greater improvement in daytime sleepiness than DLT, while DLT showed greater reduction in anxiety than BLT. For brain networks, BLT showed significant within-treatment improvement in the visual network, and DLT showed significant within-treatment improvement in the DMN. However, between-treatment comparisons did not reveal significant differences. The hypothesis that different intensities of LT affect different brain networks warrants further validation.