Life on earth is dependent on visible light radiation. Without it, food chains would fall apart and surface temperatures would plummet; although visible light is integral to our survival and is beneficial in many ways, it is capable of causing negative effects as well.
Plants rely on the energy provided by visible light to power their photosynthetic cycle, allowing them to make simple sugars from components found in their environment. Without light, photosynthetic plants would exhaust their energy supplies and die.
Besides relying on photosynthetic sources of food, humans also need sunlight to function. According to Lisa Conti of Scientific American, lack of sunlight can prevent synthesis of neurotransmitters, leading to depression and brain damage.
A study by Taylor et al. in Archives of Ophthalmology links excessive exposure to visible light, especially in the blue spectrum, to age-related macular degeneration.
On Inanimate Objects
Light in the visible spectrum can cause photodegradation of pigments and colorants. While not as powerful as UV light at causing fading, blue and violet light can cause a similar though lesser effect.
In many plastics and polymers, sunlight can cause a breakdown of the object's molecular structure, making the object brittle and opaque until it is destroyed completely.