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諸如嚴(yán)重的情緒悲傷、工作壓力等會加速身體的老化？這絕非聳人聽聞。美國加利福尼亞大學(xué)的ElissaEpel博士領(lǐng)導(dǎo)的這項研究在生物學(xué)領(lǐng)域第一次把心理緊張和心理壓力與生理年齡如此直接地聯(lián)系起來。而在上海內(nèi)分泌領(lǐng)域的專家看來，美國科研小組上個星期轟動世界的這項研究成果非常適合用來解釋中國人常說的“一夜白頭”。
【英文原文】
Your teenage son wrecks the car. Your daughter shows up with her recently paroled boyfriend.
These are the sorts of things that can make your hair turn gray overnight.
Actually, it's impossible for hair to completely change color overnight. Hair color comes from a pigment called melanin. When hair grows, the cells that form the growing hair accumulate melanin and distribute it throughout the shaft at the center of a strand of hair. The hair's color depends on the number, size, and color of the melanin particles.
Gray hair results when, for some reason, the production of melanin is reduced, or stops completely. When this happens, the hair becomes transparent and all we see are the colorless cells that make up the hair shaft. Although it is common for melanin production to decrease and eventually stop as a person grows older, there is no specific explanation as to why this happens. Heredity seems to play a significant role in determining when the cells that make hair stop making pigment. If you have inherited genes programmed to shut off the production of melanin at an early age, you'll go gray sooner than later.
The phenomenon of suddenly going gray due to stress has more to do with hair loss than with actually losing color. A significant amount of stress can cause hair to fall out prematurely. If you already have a significant amount of gray hair, the remaining dark hairs might be in a non-growing, resting phase, and thus are more likely to fall out. The sudden loss of dark hair will make it seem as though you've gone gray overnight.
