Can Bright Light Improve Sleep in Parkinson's?

Among the most common non-motor manifestations of Parkinson’s disease, sleep disturbances frequently impair quality of life, mood, cognitive performance, and safety in patients with Parkinson’s disease. Yet many have to endure these disabling symptoms because treatment options are limited and often associated with side effects.

But light therapy may offer new hope for these patients in terms of improving excessive daytime sleepiness, according to research presented last week at the 2014 American Academy of Neurology Meeting in Philadelphia.
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“Light therapy is a safe, non-pharmacological intervention associated with improvements in excessive daytime sleepiness in Parkinson’s disease,” according to lead researcher Aleksandar Videnovic, MD, MSc, of Massachusetts General Hospital in Boston and his colleagues.

They conducted a small study of 30 patients with Parkinson’s disease to examine the safety and efficacy of light therapy in treating this patient population for excessive daytime sleepiness. The mean age of patients was 63 years and all participants experienced excessive daytime sleepiness, defined as an Epworth Sleepiness Scale (ESS) score of 10 or more.

The researchers randomly assigned patients to treatment with bright light (5000 lux) or a control of dim red light (less than 300 lux). Participants received the light therapy in 1-hour sessions twice daily for 2 weeks. The patients were matched for Parkinson’s disease medications and continued their medication regimen before and throughout the intervention.

The researchers used ESS scores, the Pittsburgh Sleep Quality Index, and the Parkinson Disease Sleep Scale to assess excessive daytime sleepiness and sleep quality at treatment baseline, post-treatment (2 weeks), and 2 weeks after light therapy (4 weeks).

The mean changes in ESS scores were 4.75 in the bright-light group and 1.79 in the control group, indicating a statistically significant difference between the 2 treatments. “Exposure to bright light was associated with significant improvements in excessive daytime sleepiness,” the researchers found.

These beneficial effects persisted 2 weeks after the completion of bright-light therapy, and there was a trend toward significant improvements in sleep quality 2 weeks after completion as well.

Yet, the researchers caution that this treatment isn’t quite ready for primetime. “Further studies are needed to optimize the duration and exposure parameters of light therapy in the Parkinson’s disease population,” they said.

—Colleen Mullarkey

Reference

Videnovic A, Marconi A, Kutha T, Miskevics S, Zee P. Bright light therapy improves excessive daytime sleepiness associated with Parkinson’s disease. Neurology. 2014 Apr 8;82(10):S9.003.