How light therapy may improve symptoms of Alzheimer's disease

Light therapy, an emerging wellness trend, has been used to treat some types of depression. Now, a new study shows that it can be effective in improving sleep and psycho-behavioural symptoms in people with Alzheimer’s disease.

Along with cognitive decline, sleep disturbances and psycho-social behavioural symptoms such as apathetic and depressive behaviour and aggression are often associated with Alzheimer's disease. The study, published in the journal PLOS ONE, shows that light therapy, which refers to exposure to a bright light source, is a promising treatment option for some symptoms of Alzheimer’s disease.

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This non-pharmacological therapy is called photobiomodulation wherein light energy is used to stimulate the suprachiasmic nucleus (SCN) which is a sleep modulator in the brain, a press statement published in Science Daily explained. According to Neuroscience News, a comprehensive study involved analysis of fifteen randomized controlled trials, published between 2005 and 2022, involving 598 patients, to examine whether light therapy could be a safe and effective intervention.

The results showed that light therapy significantly improved sleep and interdaily stability—a measure of the strength of circadian rhythms—and reduced intradaily variability—a measure of how frequently a person transitions between rest and activity during the day. In people with Alzheimer’s disease, this therapy also helped in alleviating depression and reducing patient agitation as well as caregiver burden, Neuroscience News elaborated.

"Light therapy improves sleep and psycho-behavioural symptoms in patients with Alzheimer's disease and has relatively few side effects, suggesting that it may be a promising treatment option for patients with Alzheimer's disease," the study authors said in the statement.

Previous studies have also highlighted the effectiveness of light therapy in improving mood and reducing sleep disturbances. For instance, a 2020 study, presented at the American Academy of Neurology's 72nd Annual Meeting in Toronto, Canada, showed that when people with mild traumatic brain injury are exposed to early morning blue light therapy, they may experience a decrease in depression and other concussion symptoms. 

Another 2020 study, published in the journal Cephalalgia, demonstrated that green light therapy reduced pain intensity and frequency of migraine headaches and improved quality of life. These studies indicate how light therapy can be used as an effective intervention for various health issues. 

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