The Logic of the Eye

Eye-popping facts: Humans are the only primates that cry. Crying cleanses the body of toxic substances through the excretion of tears. The emotional release makes one feel better. (The average cry lasts about six minutes.)


Blinking protects the eye from dust. Blinking also occurs during learning, and increases significantly during stress -- for example, when a person is lying. The total time spent in darkness from blinking throughout the day is about half an hour.


Contrary to popular belief, sitting up close to the TV, or watching a bright screen in a dark room, will not damage the eye. The eyes get tired temporarily, but that's all.


Dreaming occurs during REM sleep, also known as paradoxical sleep. REM refers to Rapid Eye Movement under the dreamer's closed lids. Its purpose is still disputed, but some researchers think it aids in the brain's long-term data organization.

More eye-popping facts: Eye color does not change with age -- it's an illusion, caused by the pupil shrinking so that the surrounding eye (eg., the iris) appears brighter. So-called "blind spots" in the retina are caused by a bundle of nerve fibers situated in the optic nerve. The rumor that eating carrots is good for eyesight is true, because the carrot's vitamin A increases retinal, a light-sensitive chemical used in night vision. (Eating spinach is also good for lowering the risk of geriatric macular degeneration.) The pupil of the eye enlarges when it looks at something interesting, such as a pretty woman. Blue-eyed people see better in the dark than others. And, finally: no scientific evidence exists for the magical effects of the so-called Evil Eye.

Some of the facts above gleaned from The Odd Body, by Dr. Stephen Juan.

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