Project Overview

Sleep in the nursing home environment has been shown to be extremely disturbed and fragmented, in part as a result of decreased light exposure. Insufficient and/or mistimed artificial lighting can disrupt circadian rhythms, adversely affecting sleep, mood, and cognition. Elderly are more susceptible due to age-related changes in the circadian and ocular systems. In a collaboration between Simon Fraser University, the University of British Columbia, BC Hydro and Fraser Health Authority, we are examining the effects of tunable white lighting- changing in intensity (0-800 lux) and colour temperature (2700-6000K) over the 24-hour day in promoting circadian entrainment, performance and psychological well-being in older adults at the Nimi Nikkei Home, an assisted-living home in Burnaby, BC. Participants’ rest-activity cycle and sleep (tracked with actigraphy), cognitive performance (NIH toolbox) and psychological well-being (sleep quality, mood, and fatigue) will be compared in a within-subject-design consisting of two weeks of baseline (control condition with original lighting) and five weeks of experimental condition (cycled lighting), followed by three weeks of washout (control condition with original lighting).

Daily changes in the sun’s color temperature is an important signal through which the circadian system senses external time. Cycled lighting should therefore increase the effectiveness of indoor light as a circadian time cue, indicated by an increase in the amplitude of the rest-activity cycle, a gradual stabilization of sleep timing, a more normalized timing and duration, and less frequent awakenings. Also, we predict the cycled lighting to improve elderly participants’ cognitive performance and psychological well-being.