Nearly everyone knows that aging eyes need brighter light to read or even see. Now it turns out that bright indoor light, or better yet, bright sunlight, helps the body regulate all kinds of internal mechanisms influencing overall health. Older adults' eyes have a role in things as seemingly-unrelated to them as memory and depression, reports Laurie Tarkan in The New York Times.
Here's why: As we get older, the eye's lens gradually yellows and the pupil narrows. So less sunlight reaches key cells in the retina that regulate the circadian rhythm system, the body's exquisite internal clock.
Circadian rhythms, Tarkan explains, are the cyclical hormonal and physiological processes that start up in the morning and wind down at night. They regulate the release of hormones like melatonin and cortisol. Disturbed circadian rhythms are thought to have a role in conditions ranging from memory los