Light Therapy Shines in Treating Alzheimer’s Sleep and Mood Issues

Summary: A new study highlights the efficacy of light therapy in enhancing sleep and reducing psycho-behavioral symptoms in Alzheimer’s patients. This non-pharmacological treatment, targeting the brain’s sleep modulator, shows significant promise in mitigating apathetic and depressive behaviors, agitation, and aggression commonly associated with Alzheimer’s cognitive decline.

The comprehensive meta-analysis of fifteen randomized controlled trials, involving 598 patients, underscores light therapy’s potential as a safe and effective intervention. While calling for larger studies, this research marks a significant step in Alzheimer’s treatment, offering a beacon of hope for improving patients’ quality of life.

Key Facts:

  1. Light therapy notably improves sleep efficiency, stabilizes circadian rhythms, and lessens mood-related symptoms in Alzheimer’s patients.
  2. This meta-analysis included 598 patients from fifteen high-quality trials conducted across seven countries, affirming the therapy’s broad applicability.
  3. The study advocates for larger future trials to further validate light therapy’s effectiveness and safety, underscoring its potential as a promising treatment option for Alzheimer’s symptoms.

Source: PLOS

Light therapy leads to significant improvements in sleep and psycho-behavioral symptoms for patients with Alzheimer’s disease, according to a new study published this week in the open-access journal PLOS ONE by Qinghui Meng of Weifang Medical University, China, and colleagues.

The cognitive decline associated with Alzheimer’s disease is often accompanied by sleep disturbances and psycho-behavioral symptoms including apathetic and depressive behavior, agitation and aggression.

Photobiomodulation is a non-pharmacological therapy that uses light energy to stimulate the suprachiasmic nucleus (SCN), a sleep modulator in the brain.

This shows an older man taking a nap by a light box.
In patients with Alzheimer’s disease, light therapy also alleviated depression and reduced patient agitation and caregiver burden. Credit: Neuroscience News

Despite light therapy receiving increased attention as a potential intervention for Alzheimer’s, a systematic evaluation of its efficacy and safety has been unavailable.

In the new study, researchers searched multiple research databases to identify all randomized controlled trials related to light therapy intervention for Alzheimer’s disease or dementia.

Fifteen high-quality trials with available methods and relevant outcomes were selected for further analysis. The included trials were written in English, published between 2005 and 2022, and performed in seven countries. They included a combined 598 patients.

The meta-analysis of all fifteen trials found that light therapy significantly improved sleep efficiency, increased interdaily stability (a measure of the strength of circadian rhythms), and reduced intradaily variability (a measure of how frequently someone transitions between rest and activity during the day). In patients with Alzheimer’s disease, light therapy also alleviated depression and reduced patient agitation and caregiver burden.

Given the limited sample sizes in studies included in this meta-analysis, the authors advocate for larger future studies, which could also explore if bright light exposure could cause any adverse behavior in patients. They conclude that light therapy is a promising treatment option for some symptoms of Alzheimer’s disease.  

The authors add: “Light therapy improves sleep and psycho-behavioral 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.”

About this Alzheimer’s disease research news

Author: Hanna Abdallah
Source: PLOS
Contact: Hanna Abdallah – PLOS
Image: The image is credited to Neuroscience News

Original Research: Open access.
The effect of light therapy on sleep disorders and psychobehavioral symptoms in patients with Alzheimer’s disease: A meta-analysis” by Qinghui Meng et al. PLOS ONE


The effect of light therapy on sleep disorders and psychobehavioral symptoms in patients with Alzheimer’s disease: A meta-analysis


Although Alzheimer’s disease (AD) mainly affects cognitive function, it is often accompanied by sleep disorders and psychobehavioral symptoms. These symptoms, including depression, agitation, and psychotic symptoms, are prominent hospitalization causes among patients with AD. Currently, relatively more research exists on light therapy for sleep disorders, while those on psychobehavioral symptoms are gradually increasing. However, no consensus exists on these results because of the vulnerability of light therapy to multiple factors, including light intensity and duration. Thus, further research investigating this aspect is warranted.


To evaluate the efficacy of light therapy in improving sleep disorders and psychobehavioural symptoms in patients with AD.


In this meta-analysis, relevant literature was searched in Embase, the Clinical Trials Registry, Web of Science, PubMed, and the Cochrane Library up to December 2022. Furthermore, a fixed-effects model was used for data analysis.


Fifteen randomized controlled trials involving 598 patients with AD were included. In the case of sleep disorders, our meta-analysis revealed that light therapy significantly improved sleep efficiency (MD = −2.42, 95% CI = −3.37 to −1.48, p < 0.00001), increased interdaily stability (MD = −0.04, 95% CI = −0.05 to −0.03, p < 0.00001), and reduced intradaily variability (MD = −0.07, 95% CI = −0.10 to −0.05, p < 0.00001). With respect to psychotic behavior, light therapy was found to alleviate depression (MD = −2.55, 95% CI = −2.98 to −2.12, p < 0.00001) as well as reduce agitation (MD = −3.97, 95% CI = −5.09 to −2.84, p < 0.00001) and caregiver burden (MD = −3.57, 95% CI = −5.28 to −1.87, p < 0.00001).


Light therapy leads to significant improvement in sleep and psychobehavioral symptoms and is associated with relatively fewer side effects in patients with AD, indicating its potential as a promising treatment option for AD.

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  1. Light and sunshine are important to the maintenance of neuropsychiatric health and function. I have noticed that the function and mood of my demented geriatric patients in long-term care facilities are helped by regular and daily sunshine breaks.

  2. BUT– what is meant by ‘light therapy’ — what is it?
    Your illustration shows a man, supposedly asleep, with a lamp close to his head and shining light onto his face.
    That to me looks all wrong!
    Out and about in the sun during the day, and darkness at night for a good and restful sleep.

  3. I have been using the GB4000 Frequency Generator and Mopa for Huntington’s disease for 7 years. Still here… Would not be here without the Light therapy from my machine. Blessed. Please keep going with your research. You can save lives and postpone the decline of many others.

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