dementia - alzheimers - illustration

Memory, language impairment, mood changes, and apathy. These symptoms are followed by motor problems and agitation during the later stages of the disease. This is due to plaque and tangle deposition within and around the neurons. These statements describe a well-examined disease we still do not know how to treat: Alzheimer’s.

Tangles and plaque are a natural consequence of aging. In some people, it only takes decades for these substances to build up so much so that they suffer from the disorder. For others, it would take centuries to reach the necessary levels so they never experience the mental health implications. Nevertheless, provided with the right amount of time, at some point everyone would notice symptoms and succumb to the disease.

Of course, light can neither stop nor reverse these pathological processes by any means. However, it is not the loss of neurons which bothers us but the loss of their essential functions. These functions include proper sleep, good mood, and memory This is where the lamps can help! Why? Because some of these problems are related to specific Alzheimer’s damage to the eye and optic nerve, especially melanopsin cells of the retina.

As you can learn in our detailed article, melanopsin in the retina reacts to light and informs our inner clock that the day has arrived and our bodies should wake up. And by waking up, we mean releasing more chemicals which improve our alertness, mood, and cognitive skills. Therefore, light means better mood, better cognition, more increased activity. This, in turn, results in better sleep the next night. Since the natural light mechanism is weakened by Alzheimer’s, more light should help, right?

Adding more light should compensate for the lower reactivity of the retina and lower capacity of the optic nerve. Also, our inner clockwork, the suprachiasmatic nucleus, should then receive enough stimulation by light. If sufficiently stimulated, it should encourage all the respective brain centres to their various functions as they should. A higher release of hypocretin and noradrenaline should stimulate activity, thus improving vigilance and activity. More serotonin and dopamine should help with bad mood, irritability, patience, and so on.

Well, that is the theory anyway. As famously stated, while the practice and the theory are the same in theory, in practice they often differ. This is especially true in medicine. There might be some catch there or the effect might simply be too subtle for anyone to receive significant benefit. Simply: no matter how clear the theory is, we need to repeatedly check whether it truly holds up under the microscope or falls short.

Bright light therapy and Alzheimer’s: mixed results

The results are inconclusive, yet positive. Bright light therapy is mentioned in older overviews of nonpharmacological treatments of dementia that do not specifically concentrate on light. This is actually a very good sign: it is not only the “bright light enthusiasts” who study and recommend phototherapy, but also regular doctors and researchers concentrating on treating Alzheimer’s.

From 2016, we have two overviews concluding it is a possible, yet not confirmed, treatment:

“Bright light therapy has little and possibly no clinically significant effects with respect to observational ratings of agitation but decreases caregiver ratings of physical and verbal agitation,”

concludes one study.

“Further research needs to be conducted to establish the impact of bright light therapy on neuropsychiatric disturbances in AD,”

found the other one.

Nevertheless, saying A, we should not forget about B. When scientists scrutinised the evidence concerning light therapy in Alzheimer’s patients in 2014, they found literally no benefits. Although these negative results are older and may be affected by inclusion of studies using less optimal treatment protocols than we would use today, they still warn us that the effects we are hoping to find are not readily observable – and therefore not exactly stunning.

Positive recent findings

Altogether, the older evidence should lead us to skepticism. Since then, however, we have found some good news.

First, Wisconsin residential care professionals report that light therapy helps their clients suffering from Alzheimer’s:

The most significant improvement seemed to be subjective with patients reporting “The days I use it, I feel better” and staff noting more positive attitudes. Sleep diaries quantified a decrease in episodes of wakefulness from 39 the week before treatment to 15 the last week of treatment. In addition, there was improvement of targeted behaviors for insomnia from 4 pre-treatment to 0 during treatment. According to the Geriatric depression screen 15-item short form, there was an average improvement of two points. The control group showed no change or worsening in all measures.

Ederer, L. (2018). Does Bright Light Therapy Improve Quality of Life For Residents in Long Term Care Facilities?

Second, we have a brand new systematic review of literature from 2018 showing that bright light therapy is likely to improve sleep, cognition, mood, and behaviour of Alzheimer’s patients. Check the results!


Verdict: helps with sleep and depression – and maybe more

The literature on Alzheimer’s specifically remains inconclusive and we do not want to speculate about whether the hypothesized benefits will be confirmed or not. Nevertheless, there are other studies allowing us to recommend light therapy, at least for those dementia sufferers who also suffer with depression or sleep problems.

A meta-analysis reviewed in our section on insomnia has proven the benefit of bright light therapy on sleep in Alzheimer’s patients.

Extensive review on antidepressant effects in demented individuals from 2018 concluded that “bright light therapy is effective in reducing depression regardless of dementia severity.