Alzheimer's DementiaElderlyLight Therapy

Using light to improve sleep in adults with dementia

Before we start, let’s define “lux.” Even though it won’t help you understand the results of the study.


  • A lux is unit for measuring illumination of a surface.
  • You can’t a convert lux to a watt (which is power not illumination)

That said, you can convert lux to watts/sq meter

  • 1 lux = 0.001496 watts/sq. meter
  • or 1 lux = 0.0001389 watts/sq foot

Moving on, here are the details of the study.

  • 66 older adults with dementia were studied.
  • Ambient bright light of approximately 2,500 lux was delivered through a low-glare lighting system installed in the dining and activity areas. Exposure averaged 2.5 to 3 hours for the morning and evening and 8.4 hours for all-day.

And the results.

  • Night time sleep increased significantly in adults exposed to morning and all-day light.
  • The increase was greatest in adults with severe or very severe dementia: +16 minutes for morning, and +14 minutes for all-day.

The bottom line?
The authors conclude, “Bright light appears to have a modest but measurable effect on sleep in this population, and ambient light may be preferable to stationary devices such as light boxes.”

Unfortunately, it’s impossible for an average guy (like me) to understand precisely how much light was used and how it differed from the average amount of light nursing home patients are exposed to.

However, the light delivery method required remodeling the activity and dining areas. So, there was a lot of effort (and expense) for a few extra minutes of sleep.

Was it worth the effort? I don’t know. The researchers suggest it’s something to consider when building new facilities or remodeling.

11/27/07 20:35 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.