Why Light Can Have a Calming Effect on Dementia Patients


Alzheimer’s disease not only takes away memories from those affected but also robs them of sleep. Some struggle to find peace in the evening, while others wander at night. Even in the early stages of the disease, 70 percent of patients report sleep problems.

In dementia, nerve cells and their connections in the brain die off, and the sleep center is also affected. As Alzheimer’s disease progresses, the distinction between day and night blurs further, with individuals increasingly jolting awake at night and nodding off more frequently during the day.

According to a recent review in the journal Plos One, the solution could be quite simple: a bright lamp in the room.

The sleep center typically sets the internal clock to a 24-hour rhythm, controlling sleep and wake times with the help of daylight. Older individuals are already prone to sleep rhythm disturbances.

Often, their mobility is limited, their vision deteriorates, and they have fewer social contacts, so they venture outside less frequently, receiving insufficient exposure to the daylight regulator.

These issues become worse due to the brain damage dementia causes. Researchers from Weifang Medical University in the Chinese province of Shandong examined 15 studies in which a total of almost 600 patients were repeatedly exposed to bright light through the use of special lamps.

Apparently, contact with their sun-like light has several measurable effects: the treated individuals fell asleep less frequently during the day, woke up less often at night, and experienced more restful sleep. Above all, they returned to their natural rhythm, becoming tired at a similar time each day and waking up at the same time.

Alzheimer’s disease leaves its trail of destruction along characteristic paths in the brain. It begins with changes in smells because nerve cells in the olfactory center of the brain die first. Then the process affects the hippocampus, the manager of memories and learning.

Damage to the parietal lobe, the brain area at the top of the head, leads to initial orientation disorders. The loss of face recognition comes next, after which the sleep center in the hypothalamus disconnects.

Light therapies apparently stimulate the compromised nerve cell connections and may regenerate them to some extent. And not just in the sleep center.

According to the analysis, some patients also experienced cognitive improvements. In some cases, the characteristic mood disturbances of dementia lessened, including aggression or a lack of drive. Light therapy helped both.

How exactly light should be used in treatment is unclear: therapists in the studies used light sources with a strong blue component, typical of the morning and particularly alerting, while others simply used some form of bright light.

The duration of sun substitute activation also varied greatly from study to study. The effect was compared with different control groups exposed to normal daylight, weak light therapy, or other light components.

Apart from the fact that too much light startled some patients, no side effects were found. Therefore, the Chinese researchers concluded from their analysis that light therapies have “the potential for a promising therapeutic option.” This is how researchers express themselves when they mean: It is definitely worth a try.