To generate electricity, rod cells in your eyes have some thousand power stations that burn sugar and produce electricity. In this chemical process they synthesize a substance called adenosine triphosphate (ATP) for short. It is the universal power source for every living thing, from rhubarb to clams to man. When there is need for energy - to make the heart beat, to expand the chest in breathing, to blink an eyelid - ATP breaks down into simpler substance, releasing power as it dose. As long as you lives, there will be this call for energy and ATP. Even in deepest sleep there is a torrent of activity - cellular furnaces burning to keep the body warm, brain cells discharging electricity to make dreams, heart cells pulsing to keep blood flowing. The breakdown and building up of ATP is constant.