Light Therapy May Ease the Agitation of Alzheimer’s

January 10, 2024

Exposure to bright light, or light therapy, may help people with Alzheimer’s disease sleep more soundly, according to a new report. Light therapy may also help to ease depression and some of the behavioral problems like agitation that arise as Alzheimer’s progresses. Reducing such symptoms may help to ease the burden of caring for a loved one with the disease. 

“Light therapy improves sleep and psycho-behavioral symptoms in patients with Alzheimer’s disease and has relatively few side effects,” the authors, from Weifang Medical University in China, noted. Light therapy is also far safer than antipsychotic drugs, which are often prescribed to people with Alzheimer’s to ease agitation and aggression, but which can have serious side effects. The authors conclude that light therapy “may be a promising treatment option for patients with Alzheimer’s disease.” 

For the study, published in PLoS One, researchers pooled data from 15 high-quality medical studies performed in seven countries. Participants included 598 men and women in various stages of Alzheimer’s disease. All the studies were randomized controlled trials, the gold standard of medical research, in which study participants were randomly assigned to receive either light therapy or a placebo treatment using dim light and usual care.  

The studies included two types of light therapy. In one, participants were exposed daily to light boxes that simulated natural daylight. Exposure to natural sunlight helps to reset the sleep-wake cycle and prime the brain for better sleep. Light boxes designed for lux therapy, or light therapy, have been shown to be beneficial for people with seasonal affective disorder or other forms of depression. For people with seasonal depression, exposure to bright light every morning, particularly during the winter months, can provide a boost in mood and provide sounder sleep at night. 

In another type of light therapy, researchers used specially designed goggles to deliver flashing pulses of light to stimulate electrical activity in the brain. The light targets “gamma” brain waves, which help connect and process information throughout the brain. Gamma waves play an important role in learning and memory and are diminished in people with Alzheimer’s disease. In earlier studies in animals, light flickers helped reduce levels of beta-amyloid, the toxic protein that builds up in the brains of people with Alzheimer’s disease. 

The current analysis found that either type of light therapy made it easier for people with Alzheimer’s to get a sound night’s sleep. Up to 70 percent of people with Alzheimer’s disease suffer from sleep-related problems, including agitation and daytime sleepiness. Sleep is thought to provide a cleansing function, helping to rid the brain of toxic proteins that can damage brain cells.  

Light therapy also eased symptoms of depression and reduced agitation and other behavioral symptoms of Alzheimer’s. The results were mixed regarding memory and thinking skills in people with Alzheimer’s disease, with some measures showing improvement but others showing no change.  But earlier studies found that light therapy may provide a cognitive boost for those with dementia. 

If you are interested in light therapy, you can talk to your doctor about available treatment options. Experts also recommend that those with Alzheimer’s have regular exposure to natural light in their homes during the day and go outside whenever possible.  

If you’re caring for someone with dementia, take them out for a walk during the day if possible, or allow them to sit outdoors in the sunlight. Try to bring more natural sunlight into rooms where people with Alzheimer’s spend their time, and use bright indoor lamps that use natural sunlight-simulating bulbs. The added exposure to sunlight may ease some of the symptoms of Alzheimer’s and help to make caring for a loved one with the disease a little easier. 

By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Eric Schmidt, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.  

Source: Zang L, Liu X, Li Y, Liu J, Lu Q, Zhang Y, et al: “The effect of light therapy on sleep disorders and psychobehavioral symptoms in patients with Alzheimer’s disease: A meta-analysis.” PLoS ONE, December 6, 2023 


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