Circadian rhythms impact many bodily functions, including sleep-wake cycles, hormone release and body temperature. Additionally, circadian rhythms have also been associated with sleep disorders, obesity, diabetes, depression, bipolar disorder and seasonal affective disorder.

Studies by researchers at the Lighting Research Center at Rensselaer Polytechnic Institute in New York showed that light therapy tailored to increase the circadian stimulation during the day benefited individuals with Alzheimer's disease or dementia living in long-term care settings.

Light influences these rhythms, turning on or off the genes that control the individual's biological clock.

Many people with Alzheimer's or dementia have disrupted circadian rhythms, so their sleep patterns are off and they stay awake at night, which then makes them sleepy during the day or even agitated or anxious.

Researchers at the institute found that exposure to a bluish-white light during the daytime for four weeks significantly increased sleep quality, total sleep time and reduced agitation and depression. Improved sleep means improved behavior among those affected by Alzheimer's or dementia.

Additionally, the study showed that light interventions led to improvement in appetite and calmer and more manageable behaviors. A growing number of studies have shown that better and brighter lighting can improve sundowning behaviors and also reduce sleep/wake disturbances.

The combination of damaged nerve pathways from Alzheimer's disease and the normal deterioration of the eyes due to aging means that levels of light, particularly indoors, are not usually sufficient for the internal body clock to be tuned in to the usual daily pattern. Caregivers should strive to take their loved ones affected by the disease outdoors more often, particularly in the morning hours. Also, most night lights used in the home have a yellowish tint, but night lights with a bluish light can help regulate the circadian rhythm, as it "tells" the rhythm to "wake up," which, in turn, regulates the individual's internal clock.

Researchers said that exposure to bluish-white light sources is a simple, inexpensive, non-pharmacological treatment to improve behaviors and sleep patterns in people with Alzheimer's and dementia. Aquarium lamps have the bluish-white light source and many other light sources of this type are coming on the market.

Questions about Alzheimer's disease or related disorders can be sent to Dana Territo, the Memory Whisperer, owner of Dana Territo Consulting, LLC, at