As any caregiver will know, Alzheimer's disease is associated with enormous changes in the mood, behavior, sleep patterns and activities of daily living in the person affected. Some of these symptoms have been associated with disturbances in the circadian rhythm - the term used to describe the 24 hour cycle of our biological processes. Evidence suggests that this inbuilt timing system is very sensitive to both light levels and the hormone melatonin.
A study out this month highlighting the importance of bright lighting to improve the circadian rhythm of elderly people, showed a modest improvement in their symptoms of dementia. The research, by Rixt F. Riemersma-van de Lek, M.D., and colleagues at the Royal Netherlands Academy of Arts and Science in Amsterdam, also found that the additional use of melatonin resulted in improved sleep.
Twelve elderly group care facilities were studied as to the effects of supplementary lighting and/or melatonin over 3 years. Residents with an average age of just under 86 were monitored on a number of health outcomes, including symptoms of dementia and sleep disturbances. Most residents were female and most had dementia.
In six of the care facilities ceiling-mounted bright lighting was installed and kept on for a duration of approximately nine hours a day. Participants were then randomly assigned to receive an evening dose of melatonin (2.5 mg) or placebo.
The results of the ‘bright light only' condition pointed to a lessening of cognitive deterioration by a relative five percent, a reduction in depressive symptoms by a relative 19 percent and a diminution of functional limitations by a relative 53 percent.
The effect of melatonin was reported to have a small improvement in sleep duration and to reduce the time to fall asleep. The authors of the study suggest that long term use of melatonin can only be justified in the context of a combined treatment using increased levels of illumination to suppress adverse effects on mood. The authors claim that the combined effect of melatonin and increased light levels reduced aggressive behavior by 9 percent.
Source: Rixt F. Riemersma-van de Lek et al, Use of Bright lighting in Senior Care FAcilities Associated with Some Improvement in Dementia Symptoms. JAMA. 2008;299:2642-2655.
Also see Carol Bradley Bursack's post on light levels and Melatonin for Alzheimer's.