Daytime Sleepiness in PD Helped by Bright Light Therapy
According to Aleksander Videnovic, M.D., from the Clinical Neurological Research Institute, Massachusetts General Hospital and Harvard Medical School in Boston, “Sleep disturbances are among the most common and disabling non-motor manifestations of PARKINSON’S DISEASE, affecting as many as 90% of patients.”
Sleep disturbance definitely changes the quality of life, leading to mood changes, depression, and irritability. Lack of sleep can hamper one’s awareness and lead to accidents and falls. And it is not only the patient who suffers…the caregiver’s life is turned upside down, too.
The biological clock plays an important role in other aspects of our daily lives besides affecting sleep patterns. It sets the rhythm for the hormones responsible for hunger and metabolism. It impacts heart function and can even affect the body’s immune response and how it fights infection. When sleep patterns are disrupted mood can be affected by the response of serotonin to the relation to light-dark cycles. People with seasonal affective disorder (SAD) become depressed when the days become shorter but improve when serotonin levels increase due to more available light during longer days.
Light therapy, using bright lights, has been effective in helping to relieve depression and seasonal affective disorder. Light therapy, using infrared light has also shown some effectiveness in relieving chronic pain. Because there is much clinical evidence showing positive beneficial benefit of exposure to light in both animal and human models, Dr. Videnovic designed a study for people with PARKINSON’S to evaluate their responses to light therapy.
He chose a group of 30 PARKINSON’S patients, 13 men and 17 women, who were experiencing daytime sleepiness and randomly assigned them to either a bright light therapy or a red light therapy. Sessions for both light therapy groups consisted of exposure to either bright light or red light for one hour twice a day for a period of two weeks. Subjects received their usual medications during the study. At baseline before treatment and then at the end of two weeks of treatment they were evaluated using several sleep study scales including the Epworth Sleepiness Scale (ESS) as well as the United Parkinson’s Disease Rating Scale (UPDRS) and test to measure depression. Two weeks after the end of the treatment, they were also re-evaluated.
Both groups showed only modest improvement, but the bright light therapy group showed a statistically significant improvement with average ESS score of 4.75 to the red light group score of 1.79. The bright light group also showed an improvement in the UPDRS score, which continued a small upward improvement even after two weeks.
This is a rather small study, but the results are definitely encouraging. This is a very early investigation and there may be other methods of bright light treatment that might bring more improvement. Any improvement in sleep that helps the body clock also has positive benefits on neurological functions. Further study is needed to optimize the benefits of light therapy for people with PARKINSON’S who have sleep problems and excessive daytime sleepiness.
The authors of this study presented their research results at the Annual Meeting of the American Academy of Neurology (AAN) as Abstract 13-2.004 on April 28, 2014.
“Light Therapy Effective for Daytime Sleepiness in PD” Medscape. Apr 29, 2014
Review by Marcia McCall