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Why do people feel sleepy at night? It's because a hormone, melatonin, is secreted more at night than during the daytime. That leads to another question: How does the human body know when it's time to secrete more melatonin? A team of Korean scientists may have discovered the answer: a protein that serves as a timer to set off the secretion of melatonin in the human body.
A research team led by Prof. Kim Kyong-tai and Kim Tae-don at the Pohang University of Science and Technology said on Sunday that it found that a protein in the brain that recognizes daylight creates an enzyme and another protein to induce the synthesis of melatonin at night.
Scientists know that a lack of melatonin leads to depression and insomnia, but until now they haven't understood what causes the melatonin boost at night. The latest findings are expected to help researchers develop new drugs to treat depression and sleeplessness caused by melatonin disorders.
Prof. Kim said, ¡°The pineal gland acts like a clock in the human body to recognize a change in the amount of sunlight from day to night or in different seasons. A protein secreted in the gland increases the secretion of another protein, which induces the synthesis of melatonin.¡±
When the amount of sunlight decreases, the clock tells the body that it's nighttime and sets off the alarm to start the secretion of melatonin. The research results were published in the April 1 issue of molecular biology magazine Genes and Development.
(englishnews@chosun.com )
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