Light therapy may reduce excessive daytime sleepiness and improve sleep
quality in patients with Parkinson’s disease, according to trial results published
in the April issue of JAMA Neurology. The
treatment modality is well tolerated, widely
available, and “relatively easy to prescribe
and incorporate into a clinical practice,”
said Aleksandar Videnovic, MD, a neurologist at Massachusetts General Hospital in
Boston, and colleagues.
Impaired sleep and alertness are common nonmotor manifestations of Parkinson’s disease
with limited treatment options. Patients’ sleep disturbances have been attributed to Parkinson’s disease
symptoms, adverse medication effects, and neurode-generation of central sleep regulatory areas. Altered
circadian rhythms also may play a role. Supplemental
exposure to bright light improves sleep quality and daytime vigilance in healthy older people and patients with
dementia, but the treatment modality has not been studied systematically in patients with Parkinson’s disease,
the researchers said.
One-Hour Treatment Intervals
To determine the safety and efficacy of light therapy on
excessive daytime sleepiness associated with Parkinson’s
disease, Dr. Videnovic and colleagues conducted a randomized, placebo-controlled trial.
They enrolled 31 patients with Parkinson’s disease
and excessive daytime sleepiness (ie, an Epworth Sleepi-
ness Scale score of 12 or greater). Patients were receiving
stable dopaminergic therapy and did not have cognitive
impairment or a primary sleep disorder. Investigators
randomized participants 1: 1 to receive bright light ther-
apy ( 10,000 lux) or a control condition of dim-red light
therapy (less than 300 lux). After a two-week baseline
phase, participants received light therapy
in one-hour intervals twice daily—in the
morning (between 9 am and 11 am) and in
the afternoon (between 5 pm and 7 pm)—
for 14 days. The primary outcome measure
was change in Epworth Sleepiness Scale
score from baseline. During the study,
each patient wore an actigraphy monitor
and completed a daily sleep log and vari-
ous other assessments.
During treatment, a light box was placed
86.4 cm away from the patient. Participants
were instructed to sit quietly and not nap. They could listen
to music or audiobooks.
The 31 patients ( 18 females) had an average age of
about 63 (range, 32 to 77) and an average disease duration of about six years. Among patients who received
bright light therapy, mean Epworth Sleepiness Scale score
significantly improved from 15.81 at baseline to 11. 19
post intervention. The improvement was significantly
greater than that for patients in the control group, who
had a mean Epworth Sleepiness Scale score of 15.47 at
baseline and 13.67 post intervention.
Improvements in sleep quality, latency, and fragmentation were significantly greater in the bright light therapy
group than in the control group. In both treatment arms,
light therapy was associated with increased daily physical
activity, as assessed by actigraphy, and reduced disease
severity, as assessed by the Unified Parkinson’s Disease
Rating Scale. Light therapy was not associated with significant changes in depression, anxiety, or quality of life.
In the active treatment group, one patient reported
headache, and another patient reported sleepiness. One
participant in the control group reported itchy eyes. The
adverse events resolved spontaneously, and adherence
to the study protocol was excellent, the researchers said.
Although improvement in the control arm may have been
due to the placebo effect, it is also possible that “anchoring
Light Therapy May Treat
Excessive Daytime Sleepiness
in Parkinson’s Disease
Two weeks of timed bright light therapy significantly reduced patients’ sleepiness,
compared with placebo.
Aleksandar Videnovic, MD