Circadian Rhythms and People Who Are Blind This college student, who has been blind since birth, confidently navigates her college campus with the help of her guide dog. Many people with total blindness have desynchronized circadian rhythms because they’re unable to detect the sunlight that normally sets the body’s internal biological clock, the SCN. Like sighted people deprived of all environmental time cues, blind people can experience desynchronized melatonin, body temperature, and sleep–
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