High-Intensity Environmental Light in Dementia: Effect on Sleep and Activity

Philip D. Sloane, MD, MPH; Christianna S. Williams, PhD; C. Madeline Mitchell, MURP; John S. Preisser, PhD; Wendy Wood, PhD; Ann Louise Barrick, PhD; Susan E. Hickman, PhD; Karminder S. Gill, MSPH; Bettye Rose Connell, PhD; Jack Edinger, PhD; Sheryl Zimmerman, PhD


J Am Geriatr Soc. 2007;55(10):1524-1533. 

In This Article

Abstract and Introduction


Objectives: To determine whether high-intensity ambient light in public areas of long-term care facilities will improve sleeping patterns and circadian rhythms of persons with dementia.
Design: A cluster-unit crossover intervention trial involving four conditions: morning bright light, evening bright light, all-day bright light, and minimum standard light.
Setting: The common areas of two geriatric units in a psychiatric hospital and a dementia-specific residential care facility.
Participants: Sixty-six older adults with dementia.
Intervention: Ambient bright light of approximately 2,500 lux, delivered through a low-glare lighting system installed in the dining and activity areas. Participant exposure averaged 2.5 to 3.0 hours for the morning and evening interventions and 8.4 hours for the all-day intervention.
Measurements: Nighttime sleep using wrist actigraphy and daytime activity using nonobtrusive daytime observations.
Results: Night-time sleep increased significantly in participants exposed to morning and all-day light, with the increase most prominent in participants with severe or very severe dementia (mean increase 16 minutes (P=.008) for morning, and 14 minutes (P=.01) for all-day). Morning light produced a mean phase advance of 29 minutes (P=.02) and evening light a mean phase delay of 15 minutes (P=.06). Effects on daytime sleepiness were inconsistent, and the number of sleep bouts, mesor, amplitude, intradaily variability, and interdaily stability were not significantly different, indicating that the overall strength of day and night activity rhythms did not change significantly under any treatment condition.
Conclusion: 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.


Impaired sleep is common in older persons and is associated with poorer daytime function; greater risk of mood disorders; poorer quality of life; impaired immune function; and greater rates of falls, injuries, physician visits, and healthcare costs.[1,2,3,4,5] Sleep problems are particularly prevalent in persons with Alzheimer's disease and related dementias, in whom circadian rhythm disturbances and fragmented sleep are nearly universal.[6,7,8,9] Current treatment involves prescription and over-the-counter medications, herbal remedies, and alcohol, all of which have limited effectiveness because of habituation and adverse effects.[10,11,12,13] Thus, the development of effective, safe, nonpharmacological alternatives has the potential to reduce morbidity.

Theoretically, high-intensity light therapy holds considerable promise. It is known to be the major source of entrainment of the human circadian system. In younger adults, doses of 2,000 to 3,000 lux over 1 to 2 hours will successfully treat sleep disorders due to jet lag and shift work.[13] Futhermore, bright light exposure is rare in institutionalized persons with dementia,[14,15] thereby making them a particularly suitable target for a light intervention. Although studies in patients with dementia have yielded mixed results, they have suffered from a variety of methodological problems, including small sample sizes, low dosage levels, and use of devices that require participants to remain stationary.[16,17,18,19,20,21,22,23] Moreover, it remains unclear whether morning, evening, or all-day light exerts the greatest circadian stimulus.

This article reports the result of a cluster-unit crossover intervention trial of a high-intensity lighting intervention in public areas of three care units in two facilities housing persons with moderate to advanced dementia. In both settings, dining and activity areas were modified to produce even, low-glare, high-intensity illumination throughout. Outcomes of interest were nighttime sleep and daytime activity. Four conditions were compared: morning bright light, late afternoon to early evening bright light, all day bright light, and normal (industry standard) lighting.


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