A novel viewpoint is outlined in this article, though as always it remains to be seen how important the effect is in comparison with other concrete manifestations of aging: "For decades, scientists have looked for explanations as to why certain conditions occur with age, among them memory loss, slower reaction time, insomnia and even depression. They have scrupulously investigated such suspects as high cholesterol, obesity, heart disease and an inactive lifestyle. Now a fascinating body of research supports a largely unrecognized culprit: the aging of the eye. The gradual yellowing of the lens and the narrowing of the pupil that occur with age disturb the body's circadian rhythm, contributing to a range of health problems, these studies suggest. As the eyes age, less and less sunlight gets through the lens to reach key cells in the retina that regulate the body's circadian rhythm, its internal clock. ... Circadian rhythms are the cyclical hormonal and physiological processes that rally the body in the morning to tackle the day's demands and slow it down at night, allowing the body to rest and repair. This internal clock relies on light to function properly, and studies have found that people whose circadian rhythms are out of sync, like shift workers, are at greater risk for a number of ailments, including insomnia, heart disease and cancer. ... We believe that it will eventually be shown that cataract surgery results in higher levels of melatonin, and those people will be less likely to have health problems like cancer and heart disease"