Doctors prescribe exposure to a light box in the morning. Generally the light boxes use a bright light with a frequency spectrum closely simulating the frequencies of natural sunlight. The required length of exposure depends on the severity of the winter depression. While no one is certain why this helps, scientists hypothesize that it has to do with shifting the body's internal clock. And there are many testimonials to the success of light therapy.
Sunlight is the source of all biological energy on Earth.
Plants turn light into chemical energy in the form of sugars, which fuel the entire food web. Learn about light in the photosynthetic process in the Riverdeep SimLibrary activity, Role of Light in Photosynthesis . Then see if you can draw a connection between the photosynthetic process and people's craving for light and carbohydrates during the winter. Get a free trial subscription . The spread of electricity has made it easier to light up the long winter nights.