SPECIAL SECTION—BEHAVIORAL SYMPTOMS OF DEMENTIA: THEIR MEASUREMENT AND INTERVENTION Predictors of circadian sleep-wake rhythm maintenance in elders with dementia S. C. SULLIVAN 1 & K. C. RICHARDS 2 1 Harding University College of Nursing, Searcy, 2 University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA Abstract Minimal data exists to predict which elders with dementia in nursing homes will maintain circadian sleep-wake rhythms during senescence and which elders with dementia in nursing homes will experience sleep-wake rhythm deterioration. This circadian deterioration is one of the background factors identified in the Needs-driven Dementia-compromised Behavior Model. The objective of this study was to determine predictors of circadian sleep-wake rhythm maintenance in elders with dementia residing in nursing homes. This secondary analysis identifies predictors of maintaining circadian sleep-wake rhythm in a convenience sample of 171 elders with dementia residing in seven nursing homes in the Southern United States. An autocorrelogram of the circadian sleep-wake rhythm for each participant determined whether or not the rhythm had deteriorated. Using measures of depression, cognitive function, physical and psychosocial activity, medications, and sleep apnea, as well as demographic characteristics of the sample, logistic regression determined the best predictors of rhythm maintenance. The best predictors of circadian sleep-wake rhythm maintenance in elders with dementia residing in nursing homes were physical activity ( p ¼ 0.00) and psychosocial activity ( p ¼ 0.00). The interaction term between these variables was not significant ( p ¼ 0.24). These findings suggest that providing meaningful daytime physical and psychosocial activity may assist in maintaining circadian sleep-wake rhythmicity. Additional research is needed to determine if these interventions would improve circadian sleep-wake rhythm in elders with dementia residing in nursing homes. Introduction Elders with dementia have disturbed sleep (Ancoli- Israel et al., 1994; Bliwise, 1999; Pollak & Perlick, 1991), and changes in the circadian sleep-wake rhythm are one reason for this disturbance (Ancoli- Israel et al., 1997b; Bliwise, 1999). This disruption of sleep-wake rhythms hastens nursing home placement (Pollak & Perlick, 1991), increases daytime napping which impacts daytime activities and quality of life (Ancoli-Israel et al., 1991a; Frisoni et al., 1996; Vitiello, Bliwise & Prinz, 1992), and is associated with earlier mortality (Bliwise, 1993; Bliwise et al., 1995). Circadian rhythms describe 24-hour patterns of body functions, such as sleep-wake (Schwartz, 1993). The cycle of light and dark, in addition to other factors such as mealtime patterns and activity (Moore-Ede, Sulzman & Fuller, 1982), synchronizes these rhythms to a 24-hour pattern, a process known as entrainment (Hastings, 1995). A popular method used to describe these rhythms, cosinor analysis, attempts to fit data points to a cosine wave using regression techniques and evaluates the characteri- stics of the wave (Elmore & Burr, 1993; Nelson et al., 1979). Of these characteristics, the amplitude is ‘half the difference between the highest and lowest values’ of the rhythm (Nelson et al., 1979, p. 309), while the mesor is the mean around which the rhythm wave oscillates. The acrophase is the clock time at which the amplitude occurs (Nelson et al., 1979). Elders with dementia suffer from disruptions in the circadian sleep-wake rhythm, including decreased mesor and amplitude of the sleep-wake rhythm and a shift in the acrophase to earlier in the day (Ancoli- Israel et al., 1997b; Satlin et al., 1991; Satlin et al., 1995; van Someren et al., 1996). The Needs-Driven Dementia-compromised (NDC) Behavior Model (Algase et al., 1996) suggests that circadian rhythm deterioration is one of the background factors that contribute to NDC behavior. A better understanding of this factor may provide guidance in developing Correspondence to: Sheila Cox Sullivan, PhD, RN, Associate Professor and Associate Dean, College of Nursing, Harding University, Box 12265, Searcy, AR 72149, USA. Tel: þ1 (501) 279-4670. Fax: þ1 (501) 305-8902. E-mail: ssullivan@ harding.edu Received for publication 9th December 2002. Accepted 7th April 2003. Aging & Mental Health, March 2004; 8(2): 143–152 ISSN 1360–7863 print/ISSN 1364–6915 online/04/0200143–10 ß Taylor & Francis Ltd DOI: 10.1080/13607860410001649608