Exposure to Light Promotes Sleep for People with Alzheimer’s

For many people, sleep is a given — until it’s not.

An uninterrupted night of sound sleep often eludes people with Alzheimer’s disease and related dementias. The resulting sleep disruptions can have a detrimental effect on their mood and behavior. That’s because sleep is so essential to our well-being that we literally cannot survive without it.

But exposure to natural light can help regulate circadian rhythms and promote sleep in many of the 5.8 million Americans age 65 and older who have Alzheimer’s disease.

Sleep problems

Sabra Abbott, MD, assistant professor of neurology at the Center for Circadian & Sleep Medicine at Northwestern University Feinberg School of Medicine and sleep medicine specialist at Northwestern Memorial Hospital, points to a common cause of sleep problems for people with dementia. “The strength of their circadian rhythm — the internal clock that tells us when it’s daytime and when it is nighttime — tends to decrease,” Abbott says.

That decrease combines with a decrease in their homeostatic drive, which is the pressure to sleep that builds in the body and usually leads to an uninterrupted night of sound sleep.

When the strength of these processes diminishes, sleep patterns take a hit.

“People with Alzheimer’s experience sleep fragmentation, which means they sleep in multiple, short bouts both day and night, instead of sleeping in one consolidated chunk at night,” Abbott says. They struggle with waking up in the middle of the night and not being able to go back to sleep, she adds.

This disruption in sleep patterns can have a snowball effect for people with Alzheimer’s, says James K. Wyatt, PhD, director of behavioral sleep medicine at Rush University Medical Center. “When they don’t get enough sleep at night, they are going to be sleepier during the day.”

Importance of light

Natural daylight is key for regulating circadian rhythm.

“The constant dim lighting in nursing home and hospital environments isn’t strong enough to regulate sleep patterns, but there have been a lot of studies that show that the circadian clock responds to light from the environment,” Abbott says.

People with Alzheimer’s need to experience the natural progression of light from daybreak to night to improve their sleep patterns, she says.

“It’s good to have a 24-hour cycle with the contrast between light, with dawn being the period when light is the brightest during the day and dim light and the avoidance of light at night,” Abbott says.

Caregivers should expose their loved one to as much natural light as possible during the day and limit light at night — including from light fixtures and screens — to help regulate their circadian rhythms.

Wyatt recommends that people with Alzheimer’s go outside during the daytime, when possible, or sit next to a window in the early morning when light is bright. “There is a direct, immediate stimulating effect and an effect that helps to align the circadian clock,” he says.

Because daylight hours are brief in Chicago during fall and winter, Wyatt says that people can stimulate their circadian clock by using a light therapy box, initially developed to relieve depression in people with seasonal affective disorder.

“The light level of traditional light bulbs is 100 to 300 lux, whereas the light of light boxes ranges from 5,000 to 10,000 lux — the equivalent of sunlight at dawn,” he says. “They don’t have to sit and stare at the box. You can put it between them and the television set for an hour when they are watching TV.”

While the tabletop light therapy boxes are available without a prescription, caregivers should consult with a healthcare provider before purchasing one.

To reinforce sleep patterns in people with Alzheimer’s disease, Abbott also recommends using strong cues to help people recognize the time of day. Create an active, stimulating environment with a daily routine that includes physical exercise, social interaction, and mealtimes on a fixed schedule.

“The role of sleep is important because it improves memory recall and consolidation, boosts the immune system, helps a little bit in energy conservation, repairs tissue, helps regulate digestion, and helps all of the organs function,” Wyatt says.

Sleep problems contribute to depression and sundowning in people with Alzheimer’s, he adds. Sundowning occurs when people become more agitated and even aggressive in the late afternoon and early evening, as the sun goes down.

Regulating sleep patterns in people with Alzheimer’s disease has an additional benefit, Wyatt says. “If you can get the person with Alzheimer’s disease to sleep, the caregiver will be able to sleep.”