Harvard Health Publication
HARVARD MEDICAL SCHOOL
Trusted advice for a healthier life
哈佛健康刊物
哈佛医学院
健康生活权威建议
Light at night is bad for your health, and exposure to blue light emitted by electronics and energy-efficient lightbulbs may be especially so.
夜间光线对健康不利，而暴露在由电子产品或者节能灯发出的蓝光之下，对健康尤为不利。
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.
在人工照明发明之前，太阳是主要的光线来源，人们的夜晚时间都是在（相对）黑暗中渡过。而现在，世界上大部分地方，夜晚是明亮的，所以人们就认为进入所有这些流明下是理所当然的。
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.
但是我们却为沐浴所有这些光线付出代价。夜晚，光线会使人体生物钟（昼夜节奏）混乱，影响睡眠。更严重的是，研究显示，它可能导致癌症、糖尿病、心脏病和肥胖。
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.
但是并非所有颜色的光线都有同样影响。蓝光波长－在白天是有益的，因为他们可以帮助提高注意力，提升反应时间，改善心情－这些在夜间似乎是具有破坏性的。而且带屏幕的电子产品，以及节能灯在逐渐增加我们暴露在蓝光下的时间，尤其是日落以后。
Daily rhythms influenced by light
光线影响日常节律
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.
每个人的昼夜节律都稍有不同，但是平均时长是24小时15分钟。熬夜的人的昼夜节律稍微长些，而早睡的人则达不到24小时。1981年，哈佛医学院的Charles Czeisler博士表明，日光使人体生物钟与环境保持一致。
The health risks
健康风险
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.
研究显示，一些种类的癌症（乳腺癌、前列腺癌）、糖尿病、心脏病、肥胖都与夜班工作并暴露在夜光下有关。目前尚不清楚为什么暴露在夜晚光线下对我们造成如此大的危害，但是我们确定暴露在光线下，会抑制褪黑激素的分泌，这种激素会影响昼夜节律，并且有一些实验证据（非常基础的）显示较低的褪黑激素水平可能与癌症有一定相关性。
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.
一项哈费大学的研究揭示了光线与糖尿病和肥胖的联系。研究人员将10个人的昼夜节律逐渐改变，他们的血糖水平增高，到达前驱糖尿病的状态，而且瘦素水平下降，这种激素使人在饭后产生饱腹感。
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.
甚至昏暗的灯光会影响一个人的昼夜节律和褪黑激素的分泌。仅仅是8勒克斯的亮度就会产生影响，大部分台灯都要超过这个亮度，而夜晚光线是它的2倍左右。史蒂芬*劳克雷在笔记中写到，他证实了短时间睡眠与抑郁症的关系，以及糖尿病和心血管病。
The power of the blues
蓝光的力量
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).
虽然任何类型的光线都可以抑制褪黑激素的分泌，而蓝光的力量则更为强大。哈佛研究人员和他们的同事做了一个实验，比较在类似亮度下，暴露在蓝光和绿光下6.5小时后的结果，蓝光抑制褪黑激素的程度是绿光的2倍，而且改变昼夜节律达2倍（3小时VS1.5小时）
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.
在蓝光的另一项研究中，多伦多大学的研究人员将暴露在室内亮光下，佩戴防蓝光护目镜的人与在常规昏暗灯光下，未佩戴护目镜的人做了对比，结果显示两组人的激素水平差不多，这一点更力证了蓝光对褪黑激素的抑制。建议夜班工作者和夜猫子如果佩戴防蓝光的眼镜也许可以保护自己受到伤害。低价的染色太阳镜可以防蓝光，但是同样阻挡了其它颜色，因此不适合晚上在室内戴。只阻挡蓝光的眼镜价值$80.
Less-blue light
少量蓝光的灯
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.
如果蓝光确实对健康有不良影响，那么环境问题，和对节能照明的需求，将对个人健康产生冲突。那些花体紧凑型荧光灯和LED灯比伴随我们一起长大的白炽灯泡要节能的多，但是他们产生更多的蓝光。
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.
荧光灯的物理学不能改变，但是灯泡内部的镀膜可以，因此他们生产了更热的、少量蓝光的灯。LED灯比荧光灯更节能，但是他们同样产生大量的蓝色光频谱，理查德·汉斯勒，克利夫兰约韩·卡罗尔大学的光研究者写到，那些常规的白炽灯也产生蓝光，尽管要少于荧光灯。
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.
用暗红色的灯做灯，红色光线改变昼夜节律和抑制褪黑激素的力量最小 睡觉前两到三小时开始，避免看明亮的屏幕 如果上晚班或者晚上大量使用电子设备，可考虑佩戴防蓝光眼镜 白天暴露于强光下，这样将提高夜间睡眠能力，调节情绪，以及白天的警觉性
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