Light Therapy for Parkinson's disease
There has been a buzz about the potential for light therapy as a treatment for Parkinson’s disease. We had the pleasure to sit down with Yale neurologist Amar Patel to discuss this new approach.
Who is Amar Patel?
Dr. Patel is an Assistant Professor of Neurology at the Yale School of Medicine, in the division of Movement Disorders, and is a sub-investigator for the NeuroNext ENLITE PD study of light therapy for impaired sleep in Parkinson’s disease.
By jonny Acheson
Spring is well underway in the northern hemisphere, and with it the days being longer the nights are shorter. The added sunlight can mean more than just time for fun in the sun, it can mean an improvement in our mood and movement. This can have significant benefits for people with Parkinson’s disease (PWP), and this change may be a clue to ways to maintain benefits year-round.
1. What is the “body clock?”
The “body clock” is also known as the circadian rhythm, which is a natural, biological process that regulates the sleep-wake cycle and repeats about every 24 hours. The circadian rhythm is responsible for waking us up so we can be alert during the day, and making us drowsy— this is a sign that we need to get sleep to recharge for the next day. The clock can be influenced by the environment, and perhaps the most important environmental factor is our perception of the light and the dark. Our eyes capture light with specialized cells in the brain (the suprachiasmatic nuclei). We are able to sense and signal the rest of the brain using the structure and associated circuitry to know when we should be awake and when we should sleep.
2. Are PWP at risk for sleep disturbance?
Sleep disturbance is among the most common non-motor symptoms of Parkinson’s disease. Some estimate that up to 90% of PWP report such disturbances. For many, this impacts how they feel, think, and move particularly during the daytime hours. A significant cause of sleep problems in PWP may be circadian dysfunction. PWP show an advance in their circadian phase (they may sleep earlier in the day and wake earlier at night) and a reduction in nighttime levels of melatonin, a hormone that peaks in the evening and signals that the mind is ready for sleep. Melatonin is produced in the pineal gland, which communicates with the suprachiasmatic nuclei— the area responsible for the circadian rhythm. Studies also indicate that PWP have retinal changes that impair the production of the photopigment melanopsin, which is involved in the circadian rhythm responding to light/dark cycles. By these two mechanisms, PWP may be particularly susceptible to having a disruption in their circadian rhythm— and consequently their sleep quality.
3. How can PWP use light to improve sleep?
There are many prescription and non-prescription sleep medications available. Unfortunately, these medications often result in side effects— or in some cases even temporary worsening of PD symptoms. So there is a great need to develop non-pharmacologic methods of improving sleep. Light therapy may fit this bill.
Light therapy can be delivered with a light therapy box. These can be purchased at many online and brick-and-mortar retail and drug stores, starting in the range of $35 and up.
https://www.nytimes.com/wirecutter/reviews/best-light-therapy-lamp/
Light therapy boxes should be designed to filter out UV light, which can be harmful. Light therapy is otherwise generally safe, with only mild potential side effects of headache or eye strain reported. The effectiveness of light therapy depends on the amount of time spent in front of the light, the light’s intensity, and the type of light delivered. This can be thought of as the “dose” of light therapy given. The exact optimal dose for PWP is not currently known. However, studies have investigated light intensity ranges up to 10,000 lux (a measure of how bright light is) and for 30 to 90 minutes a day. These boxes were used daily or twice daily over a few weeks to months, and showed that PWP may experience improvement in insomnia, sleep quality, and sleep-wake cycle regulation. In addition, some studies suggested PWP showed improvement in motor score testing as well. Studies are underway to determine the optimal dosing and amount of benefit one might expect to receive.
4. How do I use a light therapy box?
During a session of light therapy, you sit near the box so that the light can enter your eyes indirectly. It is best not to look directly at the light, since bright light can damage or strain your eyes. Keep the box approximately 2 feet from your face. Try to keep a schedule for when you plan to use the box each day and for how long. Consistency of use is likely a key to its effectiveness. While seated in front of the box you can watch TV, read, or eat a meal. In this way, it becomes a part of your routine. For a bright light at 10,000 lux, a session of 20 to 30 minutes is likely sufficient. Scheduling the session first thing in the morning, right after you wake, may be most effective as this reinforces your brain with the signal to “wake up.” Don’t be discouraged if you don’t have a light box or can’t afford one. While a light box may be a good option for PWP in cold weather climates with long winters and limited daytime hours, thankfully the sun is right outside your door and free to use for your light therapy year-round. Try to schedule time outside in your daily routine (each morning). This time gives you a chance to achieve natural light exposure, and perhaps add some physical activity by getting outdoors. Stay safe in the sun by using sunblock, to protect yourself from harmful effects of UV light. Remember there is a higher risk of melanoma in Parkinson’s disease.
5. Can light therapy help symptoms besides
sleep disturbance?
In addition to sleep, the circadian rhythm can impact other non-motor symptoms of Parkinson’s. These include daily oscillations of autonomic function (for example, blood pressure or gut motility) and psychiatric symptoms (anxiety, depression). While the effects of light therapy on autonomic function is not clear, light therapy has been used to treat seasonal affective disorder. This is a condition in which patients develop the symptoms of depression during the winter months of short days and long nights, which tends to improve as spring arrives. Light therapy can help some patients with this condition as much as anti-depressant medications. Research suggests that the benefits of light therapy come from improvement in the regularity of the circadian rhythm, but also non-circadian mechanisms that have yet to be identified. In PWP, some studies suggest light therapy has a direct effect on dopaminergic pathways in the brain, allowing PWP to use less L-DOPA during the day. However, more research is needed to support these findings.
To read more books and articles by Michael S. Okun MD check on Twitter @MichaelOkun and these websites with blogs and information on his books and http://parkinsonsecrets.com/ #Livingwith Parkinson’s #EndingPD #Parkinsonsecrets #LessonsFromTheBedside
He also serves as the Medical Advisor for the Parkinson’s Foundation.
To see more on Dr. Indu Subramanian she does live interviews of experts in Parkinson’s for the PMD Alliance.
