Light Res Technol

In addition to stimulating the visual system, light incident on the retina stimulates other biological functions, also referred to as non-visual responses. Among the most notable biological functions are human circadian rhythms, which are bodily rhythms that, in constant darkness, oscillate with a period close to, but typically slightly longer than 24 hours. Twenty-four-hour light-dark patterns incident on the retina are the major synchronizer of circadian rhythms to the local time on Earth. Entrainment of circadian rhythms has been implicated in health and well-being. Light can also elicit an acute alerting effect on people, similar to a "cup of coffee." This review summarizes the literature on how light affects entrainment and alertness and how it can be used to achieve these aims.R01 AG034157/AG/NIA NIH HHS/United StatesR01 OH010668/OH/NIOSH CDC HHS/United StatesT32 AG057464/AG/NIA NIH HHS/United States2019-01-01T00:00:00Z30416392PMC6221201vault:3112