Creating the right light for older people

In the first part of our review, we considered the issues surrounding lighting and visual performance for the elderly. Most of these issues have been well explored for 50 years or more – and our knowledge base is fairly well established. However, when it comes to the psychological and physiological effects of lighting on humans – and the potential for the therapeutic use of lighting with the elderly – much of the relevant research is very recent, and there is much still to learn. In particular the circadian effects of lighting, and the way that these influence our sleep, health, and wellbeing, have been established for little more than 15 years. So, while lighting design guides are available to assist the visual performance of the elderly in residential facilities, to date much less attention has been given to the kinds of lighting that would facilitate the beneficial photo-biological effects of light. This clearly needs to change.

Strong blue content

Recent research has established that bright light with a strong blue content, best supplied by daylight, and a robust 24-hour daily pattern of light-dark, are essential to maintaining our biological rhythms – and ultimately our bodily health and well-being. All living organisms have biological rhythms that repeat approximately in 24-hour cycles, in accordance with the cycle of sunlight. The most common way of assessing whether a body is entrained in this circadian cycle is by measuring melatonin secretion, cortisol, and core body temperature.