久久久无码人妻精品无码_6080YYY午夜理论片中无码_性无码专区_无码人妻品一区二区三区精99

chinadaily.com.cn
left corner left corner
China Daily Website

Eyes offer clues to ills of old age

Updated: 2012-03-04 07:49
( The New York Times)

Eyes offer clues to ills of old age

For decades, scientists have looked for explanations as to why memory loss, slower reaction time, insomnia and even depression occur with age. They have investigated such suspects as high cholesterol, obesity and an inactive lifestyle.

Now research supports a largely unrecognized culprit: the eye.

As the eyes age, less and less sunlight gets through the pupil and lens to reach cells in the retina that regulate the body's circadian rhythm.

"We believe the effect is huge and that it's just beginning to be recognized as a problem," said Dr. Patricia Turner, an ophthalmologist in Leawood, Kansas, who with her husband, Dr. Martin Mainster, a professor of ophthalmology at the University of Kansas Medical School, has written extensively about the effects of the aging eye on health.

Eyes offer clues to ills of old age

Circadian rhythms are the physiological processes that rally the body in the morning to tackle the day's demands and slow it down at night. This internal clock relies on light. Studies have found that people whose circadian rhythms are out of sync, like shift workers, are at greater risk for ailments like insomnia, heart disease and cancer.

"Evolution has built this beautiful timekeeping mechanism, but the clock is not absolutely perfect and needs to be nudged every day," said Dr. David Berson from Brown University in Providence, Rhode Island.

So-called photoreceptive cells in the retina absorb sunlight and transmit messages to a part of the brain called the suprachiasmatic nucleus (SCN), which governs the internal clock. The SCN adjusts the body by initiating the release of the hormone melatonin in the evening and cortisol in the morning. Melatonin is thought to have many health-promoting functions.

Dr. Berson's team discovered in 2002 that cells in the inner retina had photoreceptors that communicated more directly with the brain and were especially responsive to the blue part of the light spectrum.

In a study published in The British Journal of Ophthalmology, Dr. Mainster and Dr. Turner estimated that by age 45, the photoreceptors of the average adult receive just 50 percent of the light needed to fully stimulate the circadian system. By age 55, it dips to 37 percent, and by age 75, to a mere 17 percent.

Eyes offer clues to ills of old age

"Anything that affects the intensity of light or the wavelength can have important consequences for the synchronization of the circadian rhythm, and that can have effects on all types of physiological processes," Dr. Berson said.

One study, published in the journal Experimental Gerontology, compared how quickly exposure to bright light suppresses melatonin in women in their 20s versus in women in their 50s. The amount of blue light that significantly suppressed melatonin in the younger women had absolutely no effect on melatonin in the older women.

Researchers in Sweden studied patients who had cataract surgery to implant clear intraocular lenses. They found that the incidence of insomnia and daytime sleepiness was significantly reduced.

Dr. Mainster and Dr. Turner believe that with age, people should make an effort to expose themselves to bright sunlight or bright indoor lighting when they cannot get outdoors. Older adults are at particular risk, because they spend more time indoors.

"In modern society, most of the time we live in a controlled environment under artificial lights, which are 1,000 to 10,000 times dimmer than sunlight and the wrong part of the spectrum," Dr. Turner said.

In their own offices, Dr. Mainster and Dr. Turner have installed skylights and extra fluorescent lights to help offset the aging of their own eyes.

The New York Times

 
8.03K
 
...
...
...
久久久无码人妻精品无码_6080YYY午夜理论片中无码_性无码专区_无码人妻品一区二区三区精99

    国产一区二区在线电影| 中文字幕亚洲一区二区av在线| 日产国产高清一区二区三区| 日韩限制级电影在线观看| 麻豆国产欧美一区二区三区| 日韩美女一区二区三区四区| 国产精品主播直播| 国产精品网友自拍| 欧美午夜精品一区二区三区| 日韩av在线发布| 久久久久国产免费免费| jlzzjlzz亚洲日本少妇| 亚洲自拍偷拍av| 在线综合亚洲欧美在线视频| 国产在线播放一区| 亚洲人成小说网站色在线| 欧美日韩在线三级| 韩国欧美国产1区| 中文字幕在线观看一区二区| 欧美少妇bbb| 韩国精品主播一区二区在线观看| 亚洲欧洲一区二区在线播放| 欧美日韩在线播放一区| 精品一区二区三区免费视频| 亚洲视频一二三区| 91麻豆精品国产91久久久更新时间| 国产乱色国产精品免费视频| 亚洲欧美日韩人成在线播放| 日韩美一区二区三区| fc2成人免费人成在线观看播放 | 成人精品免费看| 亚洲风情在线资源站| 精品人伦一区二区色婷婷| 91美女在线看| 久久超级碰视频| 一区二区三区久久久| 久久无码av三级| 欧美性猛片xxxx免费看久爱| 国产在线精品一区二区不卡了| 亚洲精品国产第一综合99久久| 精品日韩在线一区| 色婷婷综合久久久中文字幕| 激情综合色综合久久| 亚洲精品日日夜夜| 国产午夜精品美女毛片视频| 欧美色网站导航| 成人av在线电影| 奇米精品一区二区三区在线观看一| 中文字幕国产精品一区二区| 在线成人av影院| 色综合天天狠狠| 国产一区二区精品久久| 一区二区三区中文字幕在线观看| 久久精品在线观看| 欧美人伦禁忌dvd放荡欲情| a级精品国产片在线观看| 另类小说综合欧美亚洲| 亚洲一区二区视频| 亚洲欧洲精品一区二区三区| 久久久三级国产网站| 欧美精品色综合| 日本道免费精品一区二区三区| 国产不卡视频在线播放| 青青草国产精品97视觉盛宴| 亚洲免费av高清| 国产精品女同互慰在线看| 日韩一区二区中文字幕| 欧美视频在线观看一区| 99精品视频在线观看免费| 国产真实乱对白精彩久久| 日韩av一区二| 亚洲成av人片在线| 亚洲精品视频观看| 国产精品国产三级国产普通话99| 久久影院午夜片一区| 日韩亚洲欧美成人一区| 欧美日韩美少妇| 欧美在线观看视频在线| 97aⅴ精品视频一二三区| 成人永久免费视频| 国产一区二区三区免费看| 日一区二区三区| 婷婷开心激情综合| 一级做a爱片久久| 伊人婷婷欧美激情| 亚洲黄色免费电影| 亚洲免费观看高清在线观看| 中文字幕在线观看不卡视频| 国产精品国模大尺度视频| 国产精品视频免费| 中日韩免费视频中文字幕| 久久久久97国产精华液好用吗| 精品久久久久一区| 精品伦理精品一区| 精品国产一区a| 亚洲精品一区在线观看| 欧美精品一区二区三区久久久| 精品少妇一区二区三区在线播放 | 久草在线在线精品观看| 青青草原综合久久大伊人精品优势 | 中文字幕一区二区三区精华液| 久久精品亚洲麻豆av一区二区| 久久久亚洲午夜电影| 久久久久亚洲蜜桃| 久久久久久久久久久久久女国产乱| 欧美精品一区二区三区久久久| 26uuu久久天堂性欧美| 精品久久久久久久一区二区蜜臀| 日韩精品一区二区三区老鸭窝| 精品久久久久久久久久久久包黑料 | 日韩一区二区三区在线视频| 日韩视频免费直播| 精品久久久久久久人人人人传媒| 精品第一国产综合精品aⅴ| 久久久午夜精品理论片中文字幕| 国产亚洲一二三区| 国产女主播一区| 国产精品久久久久久一区二区三区| 一区在线播放视频| 一区二区三区美女视频| 五月天精品一区二区三区| 奇米影视7777精品一区二区| 精品影院一区二区久久久| 国产一区999| 99麻豆久久久国产精品免费| 色婷婷久久一区二区三区麻豆| 欧美亚洲国产一区在线观看网站| 欧美日韩视频一区二区| 日韩一区和二区| 日本一区二区不卡视频| 亚洲人一二三区| 香蕉乱码成人久久天堂爱免费| 麻豆一区二区三区| 国产精品99久| 91女人视频在线观看| 欧美日韩免费高清一区色橹橹 | 国产日韩一级二级三级| 亚洲欧洲精品一区二区三区不卡| 亚洲综合成人在线视频| 欧美aaa在线| 国产成人精品1024| 一本久久a久久精品亚洲| 欧美人动与zoxxxx乱| 欧美成人精品3d动漫h| 国产精品久久久久久久久晋中| 一区二区在线看| 美女诱惑一区二区| 成人综合婷婷国产精品久久蜜臀 | 日本sm残虐另类| 国产成人av电影| 欧亚一区二区三区| 欧美成人激情免费网| 综合久久国产九一剧情麻豆| 日韩精品亚洲专区| 成人在线综合网站| 欧美日本视频在线| 欧美激情艳妇裸体舞| 亚洲一区在线视频观看| 国产一区在线看| 在线观看日韩av先锋影音电影院| 精品国产一区二区国模嫣然| 一区二区三区在线观看网站| 精品一区二区日韩| 欧美在线高清视频| 国产午夜三级一区二区三| 丝瓜av网站精品一区二区 | 国产欧美一区二区三区网站| 亚洲第一二三四区| 国产成人精品综合在线观看| 欧美日韩精品一区二区在线播放| 久久婷婷国产综合精品青草| 亚洲成人中文在线| 成人理论电影网| 欧美成人综合网站| 亚洲永久免费av| 福利电影一区二区| 日韩视频一区在线观看| 亚洲精品视频免费观看| 国产高清视频一区| 欧美一区二区三区精品| 亚洲欧美日韩一区二区三区在线观看| 经典一区二区三区| 欧美日本精品一区二区三区| 中文字幕一区二区不卡 | 成人免费观看视频| 日韩一区二区高清| 亚洲一区二区三区美女| 大桥未久av一区二区三区中文| 欧美一区二区三区视频免费 | 国产精品久久久久久久久久免费看| 蜜臀av一区二区在线免费观看 | 中文字幕第一区第二区| 奇米影视7777精品一区二区| 欧美午夜精品电影| 1区2区3区欧美| 国产成人免费9x9x人网站视频| 欧美tk—视频vk| 日韩中文字幕一区二区三区| 91免费观看视频在线| 国产亚洲精品福利|