Your Bedroom Probably Isn't Dark Enough
你的卧室很可能不够暗
Every day, as sunlight streams into your eyes, trillions of tiny clocks in your cells reset. The human body uses light to correctly time myriad processes, ensuring that liver enzymes are made on schedule, hair cells divide at the right time, and blood pressure stays at a healthy level. People who don't get their daily dose of light at the right time of day can end up with worse health.
每天，当阳光流入你的眼睛时，你体内数万亿个微小的细胞时钟便会重置。人体利用光来为无数过程正确计时，确保肝酶按时生成、毛细胞在正确时间分裂、血压维持在健康水平。在一天中正确时间没有获得每日光照量的人，最终可能健康状况更差。
But for all its usefulness, researchers are increasingly realizing that light has a dark side. In 2019, one group of researchers found an association between obesity in women and any level of light exposure while sleeping. Another team reported that light at night was linked to high blood pressure, obesity, and diabetes in older adults. And in a study published in October 2025, researchers drawing on light-exposure data from fitness monitors worn by nearly 90,000 people, taking readings every minute, revealed that low ambient light during the night was linked to a higher risk of heart failure and other cardiovascular problems over about 10 years.
但尽管光很有用，研究人员越来越意识到光有其阴暗面。2019年，一组研究人员发现，女性肥胖与睡眠时任何程度的光照存在关联。另一个团队报告称，夜间光照与老年人的高血压、肥胖和糖尿病有关。而在2025年10月发表的一项研究中，研究人员利用来自近9万人佩戴的健身监测器的光照数据（每分钟读数一次）揭示，夜间环境光照水平低与未来约10年内心力衰竭和其他心血管问题的较高风险相关。
While these types of studies on their own can't prove that light caused these problems, they add to a growing body of work suggesting that good health requires a dark night.
尽管这类研究本身不能证明是光导致了这些问题，但它们为越来越多的研究增添了证据，表明健康需要黑暗的夜晚。
In the recent study, the team used the largest known database of information on personal light exposure, part of the UK Biobank data, says Angus Burns, a research fellow at Harvard Medical School and an author of the paper. The UK Biobank collects information from half a million volunteers, many of whom wore fitness trackers on their wrists for a week. Those data have fueled numerous studies linking step count with health outcomes.
哈佛医学院研究员、该论文作者之一安格斯·伯恩斯表示，在最近的研究中，团队使用了已知最大的个人光照信息数据库，该数据库是英国生物银行数据的一部分。英国生物银行收集了50万志愿者的信息，其中许多人曾在一周内佩戴腕部健身追踪器。这些数据推动了许多将步数与健康结果联系起来的研究。
However, the trackers also happened to contain a light sensor. Burns recalls discovering this fact and realizing that if he could figure out how to extract the data, he could have a minute-by-minute record of just how much light each person experienced throughout the day. Getting the information out of the binary code was tricky. "It was buried in there," he says. "It was a long journey." But when he and his colleague Daniel Windred, now a researcher at Flinders University in Australia, had it all before them, they soon realized that even though electric lights have made our evenings brighter, there were still clear differences between day and night, with some telling patterns.
然而，这些追踪器恰好也包含一个光线传感器。伯恩斯回忆发现这个事实时意识到，如果他能弄清楚如何提取这些数据，他就能获得每个人全天每分钟所经历光照的详细记录。从二进制代码中提取信息很棘手。"数据埋藏其中，"他说。"那是一段漫长的历程。"但当他和他的同事丹尼尔·温德雷德（现为澳大利亚弗林德斯大学研究员）把数据都摆在面前时，他们很快意识到，尽管电灯让我们的夜晚更明亮，但昼夜之间仍有明显差异，并呈现出一些显著的规律。
The effects of brighter lights
更亮灯光的影响
When researchers sorted people into groups based on how much light their trackers picked up between 12 a.m. and 6 a.m., they noticed something interesting. About half of people had very little light exposure at night. However, the other half were not spending that time in total darkness, and the median over the six-hour period, for people in the top 10% of light exposure, was about 100 lux---about the level of a dimly lit hotel hallway. It might be that they had fallen asleep with the TV on, or they might have been awake late and still winding down for the night.
当研究人员根据追踪器在凌晨12点至6点间捕捉到的光照量将人们分组时，他们注意到一些有趣的现象。约一半的人在夜间几乎没有光照。然而，另一半人并非处于完全黑暗中，对于光照水平前10%的人来说，这六小时期间的中位数光照度约为100勒克斯——大约相当于光线昏暗的酒店走廊水平。可能是他们开着电视睡着了，或者他们熬夜到很晚，仍在为入睡做准备。
Compared to people with dark nights, people who had brighter nights were more likely to develop heart disease or have a heart attack over the next ten years or so. The risk was greater the more light exposure they had, and the people with the very brightest nights---the top 10%---had higher risks of atrial fibrillation and stroke, says Windred. Even when the researchers took BMI, prediabetes status, and other health factors into account, the elevated risks, which ranged from about 30-60% higher depending on the condition, were still there. This suggests that light has an effect of its own.
与夜晚黑暗的人相比，夜晚更亮的人在接下来的十年左右更有可能患上心脏病或心脏病发作。温德雷德说，光照越多，风险越大，夜晚最亮（前10%）的人患心房颤动和中风的风险更高。即使研究人员考虑了BMI、糖尿病前期状况和其他健康因素，风险升高仍然存在，根据具体疾病不同，风险高出约30%到60%。这表明光有其自身的影响。
It was not merely that people were sleeping poorly and thus suffering from the health effects of sleep deprivation. "Even after adjusting for how much sleep people are getting, the light exposure was still a strong, independent predictor of these various heart diseases," Windred says.
这不仅仅是人们睡眠质量差，从而遭受睡眠不足的健康影响。"即使在调整了人们的睡眠时长后，光照仍然是这些各种心脏病的强有力的独立预测因素，"温德雷德说。
That tallies with what other, smaller studies with personal light sensors have found, says Dr. Phyllis Zee, a professor of neurology at Northwestern University who studies sleep and circadian rhythms. She helped lead the earlier study of about 500 older adults that found light at night was associated with an elevated risk of obesity, diabetes, and hypertension. In another study of about 700 pregnant women, she and her colleagues found that more light exposure before bedtime was linked to higher risk for gestational diabetes. There does seem to be something damaging about light at night. "The UK Biobank study really confirms that in even a larger sample," she says.
西北大学研究睡眠和昼夜节律的神经学教授菲利斯·齐博士表示，这与使用个人光线传感器的其他较小规模研究的发现一致。她曾协助领导一项针对约500名老年人的早期研究，该研究发现夜间光照与肥胖、糖尿病和高血压的风险升高有关。在另一项针对约700名孕妇的研究中，她和同事们发现睡前更多光照与妊娠期糖尿病风险升高相关。夜间光照似乎确实具有某种损害性。"英国生物银行的研究确实在一个更大的样本中证实了这一点，"她说。
The question is, why? What exactly is light doing?
问题是，为什么？光到底在做什么？
A state of constant alert
持续警觉状态
Light at night may be interfering with the circadian clock in some way, perhaps by stopping the production of melatonin, a hormone that helps differentiate day from night. Melatonin production can be delayed or arrested by even brief flashes of bright light entering the eye, research has shown. The amount of light these people were exposed to might not seem like much. But in the context of how humans evolved, it could be meaningful, says Burns. "We're getting light at night orders of magnitude brighter than the moon or campfire," he says.
夜间光照可能会以某种方式干扰昼夜节律钟，可能是通过阻止褪黑激素的生成，这是一种有助于区分昼夜的激素。研究表明，即使是短暂的强光进入眼睛，也可能延迟或中止褪黑激素的产生。这些人所接触的光照量可能看起来并不多。但伯恩斯说，从人类进化的角度来看，这可能意义重大。"我们在夜晚获得的光照，其亮度比月光或篝火要高出几个数量级，"他说。
At the same time, during the day, which we mostly spend inside, "we're getting daylight exposure that is orders of magnitude lower than what the sun gives us," Burns says. The researchers found that having very bright days, probably with lots of time spent outside, and very dark nights may protect against heart problems.
与此同时，在我们大部分时间待在室内的白天，"我们获得的白日光照射量比太阳给予我们的要低几个数量级，"伯恩斯说。研究人员发现，白天非常明亮（可能有很多时间在户外度过）并且夜晚非常黑暗，可能有助于预防心脏问题。
But there may be other factors in play, beyond disrupting the circadian clock. Zee and her colleagues uncovered something surprising when they had young, healthy volunteers sleep in the lab for one night. Some volunteers slept in ambient light of about 100 lux and some in only 3 lux, which is close to total darkness. While heart rates usually go down while we're sleeping, the heart rates of the bright-light volunteers stayed high. When the researchers tested the volunteers' metabolisms the next day, they found that the brighter light sleepers' pancreases were having to work harder at making insulin to keep blood sugar in check. "It was almost like being in a heightened state," Zee says. The nervous system, alerted by the light, seemed to stay ready for action.
但除了扰乱昼夜节律钟外，可能还有其他因素在起作用。齐和她的同事让年轻健康的志愿者在实验室睡了一晚，发现了一些令人惊讶的情况。一些志愿者在约100勒克斯的环境光下睡觉，另一些则在仅3勒克斯（接近完全黑暗）的环境中睡觉。虽然我们睡觉时心率通常会下降，但明亮光线下的志愿者心率却保持高位。当研究人员第二天测试志愿者的新陈代谢时，他们发现光照更亮的睡眠者的胰腺不得不更努力地工作以产生胰岛素来控制血糖。"这几乎就像处于一种高度警觉状态，"齐说。被光线唤醒的神经系统似乎一直准备着采取行动。
Indeed, in previous work, Windred, Burns, and colleagues found that rates of Type 2 diabetes were elevated in the UK Biobank volunteers who had brighter nights, which also points to a role for metabolism. Windred speculates that there is extra stress put on both the cardiovascular system and metabolism by light when the body doesn't expect it, and over time, that extra stress leads to damage. There might be ways to mitigate the effects, says Kenji Obayashi, a professor of epidemiology at Nara Medical University School of Medicine in Japan who studies light exposure, who was not involved in the study but finds the results intriguing. "It will be important to examine the results of interventional studies that reduce nighttime light exposure, such as using eye masks, blackout curtains, or shutters to block indoor and outdoor light from reaching the retina at night," he says.
确实，在之前的工作中，温德雷德、伯恩斯及其同事发现，在英国生物银行志愿者中，夜晚更亮的人2型糖尿病发病率升高，这也指向了新陈代谢的作用。温德雷德推测，当身体没有预期时，光照会给心血管系统和新陈代谢带来额外的压力，久而久之，这种额外的压力会导致损害。日本奈良医科大学流行病学教授、研究光照暴露（未参与此项研究但对其结果很感兴趣）的小林宪司表示，可能存在减轻这些影响的方法。"考察那些减少夜间光照的干预性研究结果将非常重要，例如使用眼罩、遮光窗帘或百叶窗来阻挡室内外光线在夜间到达视网膜，"他说。
The conclusions researchers can draw from these studies so far are limited by the data. Zee's study was only a single night, and the UK Biobank data include only a single week of light exposure. Having light-exposure data for thousands of individuals over thousands of nights, as well as lengthier lab-based studies, would help researchers get to the bottom of the link between brighter nights and poor health.
迄今为止，研究人员能从这些研究中得出的结论受到数据的限制。齐的研究只是一晚，而英国生物银行数据只包含一周的光照暴露信息。拥有数千人、数千夜的连续光照暴露数据，以及更长期的实验室研究，将有助于研究人员彻底弄清更亮的夜晚与不良健康之间的联系。
"Electric lighting is totally aberrant to our biology. It's brand new, essentially, on the evolutionary scale, that we have light at night in this way," says Burns. It has led to situations that the body is ill-equipped for, even if the details are still fuzzy to scientists. So if you find yourself regularly up late at night, basking in the TV's glow, you might be doing more than just depriving yourself of sleep. "Just take yourself back to an ancestral human and our connection with the solar day, which is where our biology developed," Burns says. Was an ancestral human bathing in light at midnight? "Probably not."
"电灯照明与我们的生物学特性完全不符。从进化尺度来看，我们以这种方式拥有夜间照明基本上是全新的，"伯恩斯说。这导致了身体无法很好应对的情况，即使其中的细节对科学家来说仍然模糊。所以，如果你发现自己经常熬夜，沉浸在电视的光亮中，你可能不仅仅是在剥夺自己的睡眠。"只需回想一下远古人类以及我们与太阳日之间的联系，我们的生物学特性正是在那里发展起来的，"伯恩斯说。远古人类会在午夜沐浴在光线中吗？"很可能不会。"
