Read the following passage and answer the questions.

Light pollution is often characterised as a soft issue in environmentalism. This perception needs to change. Light has direct impacts on us through its massive assault on health. Light at night constitutes a massive assault on the ecology of the planet, including us. It also has indirect impacts because, while 20% of electricity is used for lighting worldwide, at least 30% of that light is wasted. Wasted light serves no purpose at all, and excessive lighting is too often used beyond what is needed for driving, or shopping, or Friday-night football.

The electric light bulb is touted as one of the most significant technological advancements of human beings. It ranks right up there with the wheel, control of fire, antibiotics and dynamite. But as with any new and spectacular technology, there are invariably unintended consequences. With electric light has come an obliteration of night in much of the modern world - both outside in the city, and indoors during what was once 'night' according to the natural position of the Sun.

Life has evolved for several billion years with a reliable cycle of bright light from the Sun during the day, and darkness at night. This has led to the development of an innate circadian rhythm in our physiology.