Lay people tend to think that insomnia is usually a symptom of something else, like stress, a bad diet or a sedentary lifestyle, but this may not be true at all. It is possible that insomnia itself causes many of the conditions that it is seen as a symptom of. Using previous research that shows that insomnia causes a decrease in blood flow in the front dorsal lobe of the brain, which correlates with depression, the authors seek to establish a link between insomnia and depression.