Lighting Affects Dementia Patients’ Sleep
Individuals with Alzheimer’s disease and related dementias (ADRD) are plagued with sleep problems, nocturnal wandering, and associated daytime irritability. Preliminary studies using light therapy have shown that appropriately timed light exposure can consolidate and improve nighttime sleep efficiency, increase daytime wakefulness, and reduce evening agitation. Because the human circadian system is maximally sensitive to short-wavelength (blue) light, researchers studied lower, more targeted lighting interventions for therapeutic purposes.
Mariana Figueiro, PhD, a professor and Light and Health program director at the Lighting Research Center (LRC) at Rensselaer Polytechnic Institute in Troy, New York, designed a study to test the effectiveness of a tailored light treatment on measures of sleep, depression, and agitation in individuals with ADRD living in long term care facilities.
“A light treatment tailored to increase circadian stimulation during the day can be used to increase sleep and, therefore, quality of life in those with ADRD,” Figueiro says. “The benefits of using a more targeted light source are that lower light levels resulting in less glare and less energy use can be used to achieve the same circadian stimulation. Given that practical and effective systems such as the ones used in our study can be designed and installed, light treatments could be beneficial to those with ADRD and their caregivers.”
Because the tailored lighting system and study design were based on the theory of circadian rhythms and light’s effect on the circadian system, Figueiro was not surprised by the findings. “We expected these results to be more robust in those living in more controlled environments such as long term care residences than in those living at home because the 24-hour light exposure would be controlled,” she says.
Like Figueiro, William C. Kohler, MD, medical director at the Florida Sleep Institute in Spring Hill, Florida, and spokesperson for the American Academy of Sleep Medicine, was not surprised by the study’s results because they confirmed those of other previous studies. “They gave further substantiation to the value of properly placed bright light in improving our sleep and alertness,” he says. In fact, the sleep center employs lighting techniques to help its technicians stay alert during the nighttime hours.
The lighting schemes used in the recent study were installed in the ADRD patients’ rooms and therefore worked best for those who preferred to remain in their own rooms. Such a lighting scheme wouldn’t work, for example, for individuals who preferred to walk the halls. For these more active individuals, the development of mobile lighting applications is being considered.
For the study, modest levels (300 to 400 lux at the cornea) of a bluish-white light source (correlated color temperature [CCT] >9000 K) were installed in 14 nursing home residents’ rooms for four weeks. Custom luminaires were built for the study using parts currently available on the market. Two GE 45851 F55BX/AR/FS fluorescent lamps (GE Lighting, Cleveland) were inserted in a luminaire head (ETC 454 Line Voltage T5 fluorescent wall washer; ELCO Lighting, Los Angeles). The measured CCT of the light source was 9325 K. To save energy, all luminaires were plugged into a GE 15079v2 SunSmart Digital Timer.
Future Nursing Home Lighting
“While we don’t know everything about light’s effect on health and well-being, we know enough to apply light differently than we do now to shape our physiology and neural activity,” Figueiro says. “Current research is mature enough that we could deliver the right light at the right time to promote circadian entrainment, in order to improve health and well-being.”
The team at the Lighting Research Center has developed a 24-hour lighting scheme for elders. “Because sleep and falls are the two major issues associated with aging, this lighting scheme calls for the use of lighting systems that meet the needs of the aging visual system. It would need to deliver high circadian stimulation during the daytime and low circadian stimulation in the evening, and use nightlights that are designed to reduce falls,” Figueiro says. “The 24-hour lighting scheme could be installed right now to benefit residents; however, we need lighting manufacturers to begin developing these types of healthy lighting products that could be used to benefit human well-being. There is a critical need right now for products and applications designed to improve the lives of older adults.”
Additional Research Needed
Kohler also points out that due to dementia patients' poor sleep habits, they tend to exhaust their caregivers. Consequently, dementia patients may be placed in nursing facilities. “If we can get dementia patients to sleep better at night, then caregivers could sleep better and patients could stay in their homes longer,” he says.
— Karen Appold is a medical writer in Lehigh Valley, Pennsylvania.
Lighting: Beyond Vision
“If we are not exposed to a sufficient amount of light of the right spectrum, for a sufficient amount of time, and with the right timing, our biological clock becomes desynchronized with the solar day and we may experience decrements in physiological functions, neurobehavioral performance, and sleep,” explains Mariana Figueiro, PhD, a professor and Light and Health program director at the Lighting Research Center at Rensselaer Polytechnic Institute in Troy, New York, who recently authored a study on the topic that was presented during a poster session at SLEEP 2014 in Minneapolis. The paper is currently in press in the journal Clinical Interventions in Aging.
As humans age, changes take place in the visual system, impacting the lives of older adults in three major ways: decreased ability to see, changes in balance, and postural stability—leading to a higher risk of falls and changes in the circadian system that can impact quality of sleep. These changes can severely impact the independence of older adults. Scientists at the Lighting Research Center have developed and tested lighting recommendations that can lessen the impact of the aging eye on vision, circadian, and perceptual systems—improving task visibility (ie, the ability to see a task, such as reading a medicine bottle’s label or threading a needle) and sleep, and reducing the risk of falls.