Harvard Health Publication
HARVARD MEDICAL SCHOOL
Trusted advice for a healthier life
哈佛健康刊物
哈佛醫學院
健康生活權威建議
Light at night is bad for your health, and exposure to blue light emitted by electronics and energy-efficient lightbulbs may be especially so.
夜間光線對健康不利，而暴露在由電子產品或者節能燈發出的藍光之下，對健康尤為不利。
Until the advent of artificial lighting, the sun was the major source of lighting, and people spent their evenings in (relative) darkness. Now, in much of the world, evenings are illuminated, and we take our easy access to all those lumens pretty much for granted.
在人工照明發明之前，太陽是主要的光線來源，人們的夜晚時間都是在（相對）黑暗中渡過。而現在，世界上大部分地方，夜晚是明亮的，所以人們就認為進入所有這些流明下是理所當然的。
But we may be paying a price for basking in all that light. At night, light throws the body's biological clock—the circadian rhythm—out of whack. Sleep suffers. Worse, research shows that it may contribute to the causation of cancer, diabetes, heart disease, and obesity.
但是我們卻為沐浴所有這些光線付出代價。夜晚，光線會使人體生物鐘（晝夜節奏）混亂，影響睡眠。更嚴重的是，研究顯示，它可能導致癌癥、糖尿病、心臟病和肥胖。
But not all colors of light have the same effect. Blue wavelengths—which are beneficial during daylight hours because they boost attention, reaction times, and mood—seem to be the most disruptive at night. And the proliferation of electronics with screens, as well as energy-efficient lighting, is increasing our exposure to blue wavelengths, especially after sundown.
但是并非所有顏色的光線都有同樣影響。藍光波長－在白天是有益的，因為他們可以幫助提高注意力，提升反應時間，改善心情－這些在夜間似乎是具有破壞性的。而且帶屏幕的電子產品，以及節能燈在逐漸增加我們暴露在藍光下的時間，尤其是日落以后。
Daily rhythms influenced by light
光線影響日常節律
Everyone has slightly different circadian rhythms, but the average length is 24 and one-quarter hours. The circadian rhythm of people who stay up late is slightly longer, while the rhythms of earlier birds fall short of 24 hours. Dr. Charles Czeisler of Harvard Medical School showed, in 1981, that daylight keeps a person's internal clock aligned with the environment.
每個人的晝夜節律都稍有不同，但是平均時長是24小時15分鐘。熬夜的人的晝夜節律稍微長些，而早睡的人則達不到24小時。1981年，哈佛醫學院的Charles Czeisler博士表明，日光使人體生物鐘與環境保持一致。
The health risks
健康風險
Study after study has linked working the night shift and exposure to light at night to several types of cancer (breast, prostate), diabetes, heart disease, and obesity. It's not exactly clear why nighttime light exposure seems to be so bad for us. But we do know that exposure to light suppresses the secretion of melatonin, a hormone that influences circadian rhythms, and there's some experimental evidence (it's very preliminary) that lower melatonin levels might explain the association with cancer.
研究顯示，一些種類的癌癥（乳腺癌、前列腺癌）、糖尿病、心臟病、肥胖都與夜班工作并暴露在夜光下有關。目前尚不清楚為什么暴露在夜晚光線下對我們造成如此大的危害，但是我們確定暴露在光線下，會抑制褪黑激素的分泌，這種激素會影響晝夜節律，并且有一些實驗證據（非常基礎的）顯示較低的褪黑激素水平可能與癌癥有一定相關性。
A Harvard study shed a little bit of light on the possible connection to diabetes and possibly obesity. The researchers put 10 people on a schedule that gradually shifted the timing of their circadian rhythms. Their blood sugar levels increased, throwing them into a prediabetic state, and levels of leptin, a hormone that leaves people feeling full after a meal, went down.
一項哈費大學的研究揭示了光線與糖尿病和肥胖的聯系。研究人員將10個人的晝夜節律逐漸改變，他們的血糖水平增高，到達前驅糖尿病的狀態，而且瘦素水平下降，這種激素使人在飯后產生飽腹感。
Even dim light can interfere with a person's circadian rhythm and melatonin secretion. A mere eight lux—a level of brightness exceeded by most table lamps and about twice that of a night light—has an effect, notes Stephen Lockley, a Harvard sleep researcher. Light at night is part of the reason so many people don't get enough sleep, says Lockley, and researchers have linked short sleep to increased risk for depression, as well as diabetes and cardiovascular problems.
甚至昏暗的燈光會影響一個人的晝夜節律和褪黑激素的分泌。僅僅是8勒克斯的亮度就會產生影響，大部分臺燈都要超過這個亮度，而夜晚光線是它的2倍左右。史蒂芬*勞克雷在筆記中寫到，他證實了短時間睡眠與抑郁癥的關系，以及糖尿病和心血管病。
The power of the blues
藍光的力量
While light of any kind can suppress the secretion of melatonin, blue light does so more powerfully. Harvard researchers and their colleagues conducted an experiment comparing the effects of 6.5 hours of exposure to blue light to exposure to green light of comparable brightness. The blue light suppressed melatonin for about twice as long as the green light and shifted circadian rhythms by twice as much (3 hours vs. 1.5 hours).
雖然任何類型的光線都可以抑制褪黑激素的分泌，而藍光的力量則更為強大。哈佛研究人員和他們的同事做了一個實驗，比較在類似亮度下，暴露在藍光和綠光下6.5小時后的結果，藍光抑制褪黑激素的程度是綠光的2倍，而且改變晝夜節律達2倍（3小時VS1.5小時）
In another study of blue light, researchers at the University of Toronto compared the melatonin levels of people exposed to bright indoor light who were wearing blue-light–blocking goggles to people exposed to regular dim light without wearing goggles. The fact that the levels of the hormone were about the same in the two groups strengthens the hypothesis that blue light is a potent suppressor of melatonin. It also suggests that shift workers and night owls could perhaps protect themselves if they wore eyewear that blocks blue light. Inexpensive sunglasses with orange-tinted lenses block blue light, but they also block other colors, so they're not suitable for use indoors at night. Glasses that block out only blue light can cost up to $80.
在藍光的另一項研究中，多倫多大學的研究人員將暴露在室內亮光下，佩戴防藍光護目鏡的人與在常規昏暗燈光下，未佩戴護目鏡的人做了對比，結果顯示兩組人的激素水平差不多，這一點更力證了藍光對褪黑激素的抑制。建議夜班工作者和夜貓子如果佩戴防藍光的眼鏡也許可以保護自己受到傷害。低價的染色太陽鏡可以防藍光，但是同樣阻擋了其它顏色，因此不適合晚上在室內戴。只阻擋藍光的眼鏡價值$80.
Less-blue light
少量藍光的燈
If blue light does have adverse health effects, then environmental concerns, and the quest for energy-efficient lighting, could be at odds with personal health. Those curlicue compact fluorescent lightbulbs and LED lights are much more energy-efficient than the old-fashioned incandescent lightbulbs we grew up with. But they also tend to produce more blue light.
如果藍光確實對健康有不良影響，那么環境問題，和對節能照明的需求，將對個人健康產生沖突。那些花體緊湊型熒光燈和LED燈比伴隨我們一起長大的白熾燈泡要節能的多，但是他們產生更多的藍光。
The physics of fluorescent lights can't be changed, but coatings inside the bulbs can be so they produce a warmer, less blue light. LED lights are more efficient than fluorescent lights, but they also produce a fair amount of light in the blue spectrum. Richard Handler, a light researcher at John Carroll University in Cleveland, notes that ordinary incandescent lights also produce some blue light, although less than most fluorescent lightbulbs.
熒光燈的物理學不能改變，但是燈泡內部的鍍膜可以，因此他們生產了更熱的、少量藍光的燈。LED燈比熒光燈更節能，但是他們同樣產生大量的藍色光頻譜，理查德·漢斯勒，克利夫蘭約韓·卡羅爾大學的光研究者寫到，那些常規的白熾燈也產生藍光，盡管要少于熒光燈。
What you can do
你能做什么
Use dim red lights for night lights. Red light has the least power to shift circadian rhythm and suppress melatonin. Avoid looking at bright screens beginning two to three hours before bed. If you work a night shift or use a lot of electronic devices at night, consider wearing blue-blocking glasses. · Expose yourself to lots of bright light during the day, which will boost your ability to sleep at night, as well as your mood and alertness during daylight.
用暗紅色的燈做燈，紅色光線改變晝夜節律和抑制褪黑激素的力量最小 睡覺前兩到三小時開始，避免看明亮的屏幕 如果上晚班或者晚上大量使用電子設備，可考慮佩戴防藍光眼鏡 白天暴露于強光下，這樣將提高夜間睡眠能力，調節情緒，以及白天的警覺性
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