Non-Visual Effects of Light - Optimized Light for Health Promotion of Elderly People in Nursing Homes
Since the early 1990s it is known that humans have light-sensitive ganglion cells that have non-visual functions in the retina. These so-called intrinsic photosensitive retinal ganglion cells, ipRGCs, mainly respond to shortwave (blue) light around 480 nm, as it also occurs in natural daylight. IpRGCs play an important role in circadian rhythm by transferring light stimuli to the suprachiasmatic nucleus (SCN) in the brain, which controls biological processes. It was shown that blue light exposure, amongst others, suppresses melatonine secretion and hence notably influences the circadian rhythm. Elderly residents in nursing homes often suffer from a disturbed circadiane rhythm, which may lead to sleep disorders and may negatively contribute to dementia and depression. In the NiviL study the subjects are exposed to a spectral modified dynamic lighting, which contains a higher amount of blue light in the morning which dynamically decreases over the day – as it also occurs in natural daylight. The aim of the study is to find out, whether a dynamic, spectral modified lighting may improve health, well-being and life-quality of residents in nursing homes.