Abstract
Light is a key factor for human non-visual forming system as well as visual forming system. For example, bright light exposures at nighttime delay circadian rhythm and suppress melatonin secretion. The effects are known to depend on light intensity (dose-response curve) and wavelength (action spectrum). On the other hand, bright light at daytime advance circadian rhythms and encourage melatonin secretion. The difference of the impact between at daytime and nighttime is known as a phase-response curve. The light also has impacts on subjective wakefulness, autonomic nervous activity, central nervous activity, and so on at night. This paper reviews about the non-visual forming effects of light.
