Health19 Oct 2010 01:35 pm
Totally blind people—those who cannot perceive light—often suffer from chronic sleep disorders. They report difficulty falling asleep and staying asleep, as well as fatigue, poor concentration, and irritability while awake.
Your body has its own internal clock, called the circadian rhythym, that controls your natural cycle of sleeping and waking hours. In fact, the high prevalence of sleep problems in the blind underscores the importance of light in regulating circadian rhythms in the sighted. Luckily, more than half of these individuals-an estimated 50,000 to 100,000 people in the United States alone-may have a potentially correctable circadian-rhythm sleep disorder that can be effectively managed with Melatonin supplements.
Melatonin is a naturally occurring hormone that helps control your sleep and wake cycles. In part, your body clock controls how much melatonin your body makes. Very small amounts of it are found in foods such as meats, grains, fruits, and vegetables, so most people take it in supplement form.
In sighted people, sunlight signals travel from the eyes to the body’s master biological clock in the hypothalamus over a pathway distinct from that for vision. Shifting levels of light across the day entrain, or synchronize, the sleep-wake cycle, endogenous melatonin release, and other biological rhythms with the earth’s day/night cycle. Thus, daily exposure to sunlight automatically resets cycle length to the world’s 24-hour day.
As if being blind wasn’t bad enough, it turns out that more than half of totally blind people have a 24.5-hour circadian cycle.In effect, they commonly drift later and later around the real time clock, a phenomenon known as“ free-running.” Even if they try to sleep at regular times, they typically sleep well only a few days a month, when their internal clocks fall in sync with preferred schedules. At other times, they sleep poorly and feel drowsy while awake. Some experience depressive symptoms.
Luckily, daily oral doses of melatonin from the local GNC can entrain these blind free-runners and help improve their quality of life.
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