A modest improvement in symptoms of dementia has been associated with the use of bright light in daytime, in an effort to improve their circadian rhythms, according to a study released on June 10, 2008 in JAMA. Additionally, the use of melatonin resulted in improved sleep.

Dementia is a continuous decline in cognitive ability over time, and usually affects elderly patients. These symptoms can have many contributing factors, and according to the authors: "In elderly patients with dementia, cognitive decline is frequently accompanied by disturbances of mood, behavior, sleep, and activities of daily living, which increase caregiver burden and the risk of institutionalization."

Many biological processes in many organisms recur every 24 hours in what is referred to as a circadian rhythm. While this rhythm is internal, it can be affected by several factors including the presence or absense of daylight. In humans, levels of melatonin in the body are a classical method of measuring the circadian cycle, and sometimes melatonin is used to help maintain a regular rhythm. Disruptions to these rhythms are quite familiar, and include jet lag and Seasonal Affective Disorder (SAD.)

According to the authors, the circadian rhythm may also be associated with the symptoms of dementia in the elderly: "The circadian timing system is highly sensitive to environmental light and the hormone melatonin and may not function optimally in the absence of their synchronizing effects. In elderly patients with dementia, synchronization may be [diminished] if light exposure and melatonin production are reduced."

In an effort to evaluate the effects of circadian rhythm modification on dementia, Rixt F. Riemersma-van der Lek, M.D., of the Royal Netherlands Academy of Arts and Sciences, Amsterdam, and colleagues performed a trial in 12 different elderly group care facilities on 189 facility residents with an average age of 85.8 years. Of the total, 90% were female, and 87% of the subjects already presented with dementia. The trial examined the effects of up to 3.5 years of daily supplementation with bright light and/or melatonin on several different health outcomes, including dementia and sleep disturbances.

In six of the facilities, bright lighting was installed on ceiling fixtures. The lights were turned on every day between nine in the morning and six in the evening. The participants were a part of this trial for an average of 15 months, with a maximum period of 3.5 years. It was found that the bright light had a positive effect on cognitive deterioration by 5% relative to those without the light, while depressive symptoms were reduced by 19%. The increase in functional limitations usually experienced by those with dementia was decreased by a relative 53%.

Additionally, randomly, patients were assigned to receive evening melatonin doses (2.5 mg) or a placebo. Patients taking melatonin had a reduced time needed to fall asleep by 19%, and increased their average total sleep durations by 6%. However, caregiver ratings dropped due to withdrawn behavior and mood expression.

In combination, the bright light improved the adverse effects on mood. Ultimately, in combination with bright light, melatonin administration reduced aggressive behavior by 9% relative to those without.

The authors indicate that this shows there could be a positive effect to having brighter lights in facilities for the elderly. "In conclusion, the simple measure of increasing the illumination level in group care facilities [improved] symptoms of disturbed cognition, mood, behavior, functional abilities, and sleep. Melatonin improved sleep, but its long-term use by elderly individuals can only be recommended in combination with light to suppress adverse effects on mood. The long-term application of whole-day bright light did not have adverse effects, on the contrary, and could be considered for use in care facilities for elderly individuals with dementia," they write.

Effect of Bright Light and Melatonin on Cognitive and Noncognitive Function in Elderly Residents of Group Care Facilities: A Randomized Controlled Trial
Rixt F. Riemersma-van der Lek; Dick F. Swaab; Jos Twisk; Elly M. Hol; Witte J. G. Hoogendijk; Eus J. W. Van Someren
JAMA. 2008; 299(22): 2642-2655.
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Written by Anna Sophia McKenney