Field study of visual and biological light conditions of independently-living elderly people

A field study was carried out to learn more about the influence of light on the lives of elderly people . The results should lead to the development and design of a light concept for elderly people that will improve their everyday health and well-being. Methods: Ninetyone independently-living elderly people were questioned about their current living conditions and the possible influence of light; both the visual and the non-visual effects were considered. Daylight and artificial illuminance measurements were taken in the participants ’ living rooms at the position where they performed specific visual tasks. For the non-visual influence, vertical illuminances were measured at the position where the people spent most of their time. Results: Lighting measurements performed in the living rooms revealed levels that were too low for adequate vision and for biological stimulation. Even under daylight conditions, the lighting levels were below recommended values. Discussion: Although we would expect the elderly participants to be aware of the positive effect of light on performing visual tasks, the results do not support this; the illuminance levels were sufficient for ‘normal’ eyes but, unfortunately, not for older eyes. Surprisingly, 85% of the participants were satisfied with their lighting conditions, even though 25% actually had impaired visual acuity. Further research should show whether this impairment could be avoided by adjusted glasses to compensate for the de teriorating eye sight of the aging eye. We expected different levels of biologically-active light stimulation to reveal differences in sleep-wake patterns and sleep quality. The results show no significant effects in this area. Further research is needed to determine the precise protocol necessary to produce a biological effect via the older eye in terms of illuminance levels, wavelength, and the time of day and duration of the stimulus.