<P> 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 you age, the lens inside your 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 begins 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 . </P> <P> 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 . </P> <P> 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 . </P>

Which lighting feature in most nursing homes compromises older adults ability to function