June 11, 2008
Science Daily/JAMA and Archives Journals
The use of daytime bright lighting to improve the circadian rhythm of elderly persons was associated with modest improvement in symptoms of dementia, and the addition of the use of melatonin resulted in improved sleep, according to a new study.
"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," the author write. 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."
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by a relative 19 percent and increased total sleep duration by 6 percent, but adversely affected caregiver ratings of withdrawn behavior and mood expressions. The addition of bright light improved the adverse effect on mood. In combination with bright light, melatonin reduced aggressive behavior 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. 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," the authors write.