Researchers from the Netherlands set about to determine whether the progressive changes in symptoms seen in dementia might be affected by the 2 major synchronizers of the circadian timing system: bright light and melatonin.

First, the details.

  • 189 elderly residents of 12 group care facilities in the Netherlands participated in the study.
  • They were randomly assigned to daily treatment with whole-day bright (1000 lux) or dim (300 lux) light and to evening melatonin (2.5 mg) or placebo for an average of 15 months.
  • 90% were female and 87% had dementia.
  • Neither the patents nor the researchers knew their treatment (double-blind).

And, the results.

  • Light reduced cognitive deterioration (reasoning), depressive symptoms, and the increase in functional limitations.
  • Melatonin shortened sleep onset and increased sleep duration.
  • Melatonin had a negative effect on positive and negative affect.
  • Melatonin also increased withdrawn behavior, although this was not seen if given in combination with light.
  • Combined treatment also reduced aggressive behavior, increased sleep efficiency, and improved nocturnal restlessness.

The bottom line?

The authors concluded, “Light has a modest benefit in improving some cognitive and noncognitive symptoms of dementia. To counteract the adverse effect of melatonin on mood, it is recommended only in combination with light.”

6/11/08 21:54 JR

Hi, I’m JR

John Russo, Jr., PharmD, is president of The MedCom Resource, Inc. Previously, he was senior vice president of medical communications at, a complementary and alternative medicine website.