Bright light therapy may decrease symptoms of dementia in elderly people, a new study from Royal Netherlands Academy of Arts and Sciences, Amsterdam, has revealed.
In addition to bright light therapy, use of melatonin also improved sleep.
The elderly patients often face disturbances of mood, behaviour, sleep, and activities of daily living.
These symptoms have been associated with disturbances of the circadian rhythm (the regular recurrence, in cycles of about 24 hours, of biological processes or activities).
"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," wrote the authors.
The study led by Dr Rixt F. Riemersma-van der Lek conducted a trial at 12 elderly group care facilities in the Netherlands that evaluated the effects of up to 3.5 years of daily supplementation of bright light and/or melatonin on a number of health outcomes, including symptoms of dementia and sleep disturbances.
The study included 189 facility residents with an average age 85.8 years. Among them 90 percent were female and 87 percent had dementia.
Six of the facilities had bright lighting installed in ceiling-mounted fixtures. The lights were on daily.
The participants were randomized to receive evening melatonin (2.5 mg) or placebo and participated an average of 15 months (maximum period of 3.5 years).
The findings revealed that that bright light lessened cognitive deterioration by a relative 5 percent. It also reduced depressive symptoms by a relative 19 percent and diminished the gradual increase in functional limitations by a relative 53 percent.
Moreover, melatonin reduced the time to fall asleep by a relative 19 percent and increased total sleep duration by 6 percent, but adversely affected caregiver ratings of withdrawn behaviour and mood expressions.
In combination with bright light, melatonin reduced aggressive behaviour by a relative 9 percent.
"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," wrote the authors.
"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 added.