Melatonin is a hormone produced every evening by the brain's pineal gland. Researchers say the chemical helps facilitate the onset of sleep.
Darkness serves as a cue for the body to secrete melatonin into the blood stream and light serves as a cue to suppress it. Melatonin is not a sleep hormone but a marker of when it is time to go to sleep. Very small amounts of the hormone are also found in foods such as meats, grains, fruits, and vegetables.
There are 200,000 Americans who are completely blind. Their sleep is often disturbed. Without light cues to rely on, blind people have difficulty regulating their body clocks. They have trouble getting their sleep schedules synchronized to a 24-hour cycle and may suffer with sleep disorders, such as insomnia and daytime sleepiness. The body clocks in completely blind people shift an average of a half hour later each day. This condition, known as free-running circadian rhythms, results in irregular sleep patterns.
A new study shows a daily dose of melatonin may be able to help reset a blind person's unregulated body clock to a daily schedule. Researchers from Oregon Health & Science University randomly gave either 10 milligrams of melatonin or a placebo to seven blind people an hour before bedtime each day for three to nine weeks. After that time, the people who took the placebo first then received melatonin and those who received melatonin first then received the placebo.
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Night and day
Melatonin is a hormone that helps trigger the reflex to sleep.
 
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Researchers say no one responded to the placebo. However, the amount and the timing of the hormone was effective in regulating body clocks in six participants, allowing them to have a perfect 24-hour time schedule.
Researchers also progressively reduced the doses in three participants to the amount the body naturally produces, around .5 milligram, for four months. They found the patients were still able to sustain a normal rhythm.
Dr. Al Lewy, said melatonin acts opposite to light because it is produced naturally in darkness. If it is taken in the morning, it shifts the body clock later. If is taken in the afternoon or evening, it shifts the body clock earlier.
According to Lewy, the hormone can also be given to help those with sight who experience shift changes at jobs, jet lag, daylight-saving time adjustment problems and winter depression. There are minimal side effects, he says, though it can cause a person to feel sleepy.
However, melatonin's safety and effectiveness has not been thoroughly tested by the FDA. Most people who take the hormone and are not blind take it at the wrong time, take the wrong dose or take it for the wrong reason.
