Designing lighting for the elderly requires special consideration and care from architects and lighting designers. As people age, they experience neurodegeneration in the retina and in the suprachiasmatic nucleus (SCN). Less light reaches the back of the eyes because the pupils decrease in size as one ages, the lens inside one's eye becomes thicker, and the lens scatters more light, causing objects and colors to appear less vivid. These symptoms are particularly common with persons having alzheimer's disease. Older people also have reduced levels of retinal illuminance, such as having smaller pupils and less transparent crystalline lenses. Furthermore, as an individual ages, they begin to lose retinal neurons, which not only compromises the ability to see but also to register a robust daily pattern of light-dark that is needed to maintain biological rhythms. The 24-hour light-dark cycle is the most important external stimulus for regulating the timing of the circadian cycle. In addition to the aging eye, lighting designers need to consider the unique lifestyle needs of the elderly. It is especially important to provide strong illumination in stairwells to prevent slip and trips, for example. Due to physical limitations, they may be deprived of natural sunlight. Many nursing homes and assisted living facilities have dim, constant light levels and poor light spectra, often caused by extensive use of fluorescent lighting. Although widely used in offices and factories, it is unsuitable for clinics and homes. This can cause disruption of the body’s circadian rhythms, which can potentially lead to negative health effects. Flicker from the bulbs can be disturbing, especially for epilepsy patients, and the colour rendition is poor when compared with incandescent bulbs.
Health concerns
Accident sensitivity
Low lighting levels may contribute to slips, trips and falls in the elderly by lowering visibility of hazards such as unexpected steps, or sudden changes in floor surfaces. Obstacles to a safe passage may include clutter or ill-placed furniture, which can cause a slip or a trip. Grab bars and stair rails are obvious aids but must be visible to the user, and so such environments demand strong lighting. Falls of elderly people causes a significant number of hip joint fractures, replacement of which is a serious medical event. Depending on fall configuration, other bones may be fractured. Head injury is also possible. Falls from ladders are very common among the elderly, especially men, with potentially worse injuries owing to the greater heights involved. Fall prevention is thus an important consideration in designing homes for the elderly, and one of the most critical parts of that design process is supplying strong and effective lighting. Thus, when switched on, lights should react instantaneously, so the user is not surprised by a hidden obstacle as they moves into a kitchen or bathroom, for example. In such a case, incandescent light bulbs are preferred over fluorescent lighting, because they react instantaneously while a CFL takes time to warm up and become bright. Incandescent light bulbs also offer much greater illuminance than many other light sources, are relatively low cost and easy to install. Higher lighting levels enable users to see potential hazards before they need to take avoiding action, and so negotiate them safely and easily. Excellent colour rendering (as measured by the Colour rendering index) by such incandescent light also helps users identify colours correctly. Halogen bulbs are also available for greater efficiency, as are rough service bulbs to avoid discriminatory regulations, especially in the EU. No doubt LED lights will become an alternative source of high quality lighting in the future, but in 2013 they remain expensive for domestic use. Rough service bulbs are available in sizes up to 200 watt in all varieties of fittings. Although lifetime is generally lower than for CFLs, they are replaced easily. But lighting should also be free from glare and highlights so as not to distract or even temporarily blind the user. Some skill is needed to meet the several criteria governing good lighting systems, especially for senior citizens and patients. Lighting ergonomics attempts to address the problem of designing safe light environments as well as specific lighting products.
Circadian entrainment Underlying the foundation of light as therapy is the understanding that all living organisms have biological rhythms that repeat approximately in 24-hour cycles, in accordance with the cycle of sunlight. The most prominent way to measure whether a body is entrained in this circadian cycle is by measuring melatonin secretion, cortisol, and core body temperature. The suprachiasmatic nucleus (SCN) regulates melatonin and temperature and typically produces melatonin at night. Melatonin informs the body when it is time to sleep. When circadian cycles become disrupted (due either to too little light or too much light at the wrong time of day), melatonin is produced at disrupted times. This causes an individual to experience disrupted sleep patterns, which in turn causes numerous health issues to arise. The key external stimulus is variation in light and darkness over the course of the day. The elderly are at high risk for physical ailments when their circadian cycles are disrupted. Impairment of these SCN-mediated circadian rhythms becomes increasingly common with advancing age, diminished health, and Alzheimer's disease, thereby contributing to the high prevalence of sleep disturbances in these populations.
… excerpt ends here. Continue reading the full article.
