为了你的肝脏，假期里的睡眠和饮食也别太放纵
脂肪肝病例中，脂肪在肝脏组织内堆积。睡眠或饮食即便只出现短期变化，就像在假期里常常发生的一样，肝脏促进脂肪消化的能力也会受到影响。
假期里，很多人都会饮酒、熬夜、吃下额外的馅饼、睡懒觉。这些行为尽管很有趣，但却会导致生物钟，也就是让身体功能与外部环境相协调的反馈环出现变化。
肝脏是帮助调节身体新陈代谢的器官，不健康的睡眠模式、饮食方面的变化或者饮酒，都会扰乱它的节奏。如果你正在经历消化不良，或者在参加多个假日派对之后变得无精打采，那你的肝脏可能失调了。近年来，生物钟学领域的研究日益表明，为自有其生物钟的肝脏着想，保持规律的作息习惯非常重要。生物钟学是关于生理节奏的科学。生物钟在帮助肝脏全天候调节身体需求方面，例如在饭后储存能量、在睡觉时释放能量，发挥着重要的作用。
2016年7月1日，《美国生理学杂志·胃肠与肝脏生理学分册》发表拉什大学和西北大学的研究报告【1】探讨了酒精如何影响生物钟，发现夜班工人连续一周每天喝两到四杯红酒后，生物钟出现了变化，肠道内壁比白班工人更容易破损，这可能会让他们面临罹患酒精性肝病的风险。该研究作者认为：任何一个经常让生物钟出现两小时以上变动的饮酒者都面临着这种风险，人们不必上几个月或几年的夜班，只要在相对较短的时间里有一系列糟糕的行为，就有可能将自己置于风险之中。
其他一些以小鼠为对象的研究影响了人们对肝脏循环的理解。
2017年1月10日，《细胞·代谢分册》发表瑞士（洛桑联邦理工学院、雀巢健康科学研究院、洛桑大学）和法国（国家科学研究中心蒙彼利埃分子遗传学研究所）的研究报告【2】发现小鼠肝细胞中有超过500种蛋白质会在一天之中出现丰富的变化。这些蛋白质最终会帮助肝脏过滤血液、处理脂肪和糖，当其紧凑的节奏被扰乱时，肝脏可能在解毒、消化等重要过程中滞后。
人们每天的肝脏循环由睡眠、食物和酒精之间的相互作用塑造。睡眠会影响大脑中的主生物钟。像人体的其他器官一样，肝脏在某种程度上被这个主生物钟主宰着。但是，肝脏也有自己的内部生物钟，后者会受到食物和酒精的影响。
2015年11月1日，《细胞与分子胃肠病学和肝脏病学》发表东北俄亥俄医科大学以小鼠为对象的研究报告【3】发现睡眠和饮食的短期变化都会影响到肝脏促进脂肪消化的能力。一些长期干扰可能导致脂肪在肝脏中堆积，进而引发许多不同的问题：脂肪肝、糖尿病、肥胖、心脏病乃至癌症。
2015年10月14日，《生物分子》发表阿拉巴马大学伯明翰分校的研究报告【3】发现酒精还能让小鼠肝脏的运行节奏失常，小鼠被喂食适量酒精满一个月后，其肝脏生物钟会被严重扰乱。
密歇根大学生理学专家称：要让肝脏的生物钟在这个假期里如常运转，就得避免极端行为。这意味着要保持规律的作息时间，从而让主生物钟维持常态。可以稍微晚睡一会儿，但尽量别比正常就寝时间晚两小时以上。一个管用的小贴士是早上出门散步。沐浴在阳光里是对人体内部生物钟进行重置的最有效方式。
这还意味着始终清醒地认识到食物和酒精会如何影响肝脏的生物钟。少喝一点酒没什么问题，但要避免酗酒，其定义是在两个小时内饮酒四或五杯以上。
从短期来看，遵守这些准则或许可以在假期结束后较为容易地回归现实。从长期看，规律作息、少饮酒可以保护新陈代谢、预防疾病。
谁有新年计划了吗？
翻译：李琼（纽约时报）
参考文献
Swanson GR, Gorenz A, Shaikh M, et al. Night workers with circadian misalignment are susceptible to alcohol-induced intestinal hyperpermeability with social drinking. Am J Physiol Gastrointest Liver Physiol. 2016;311(1):G192-201.
Wang J, Mauvoisin D, Martin E, et al. Nuclear proteomics uncovers diurnal regulatory landscapes in mouse liver. Cell Metab. 2017;25(1):102-117.
Ferrell JM, Chiang JY. Short-term circadian disruption impairs bile acid and lipid homeostasis in mice. Cell Mol Gastroenterol Hepatol. 2015;1(6):664-677.
Udoh US, Valcin JA, Gamble KL, et al. The molecular circadian clock and alcohol-induced liver injury. Biomolecules. 2015;5(4):2504-2537.
The New York Times. 2016 Dec 27.
Your Liver Doesn't Know It's the Holidays.
Steph Yin.
Fat accumulation in liver tissue in a case of fatty liver disease. Even short-term changes in either sleep or diet, like those that occur during the holidays, can affect the liver's ability to contribute to fat digestion.
Over the holidays, many of us will drink, stay up past bedtime, eat an extra slice of pie and sleep in. Fun as they are, these activities can tamper with our circadian rhythms, the feedback loops that sync our body's functions to our external environment.
The liver, which helps regulate your body's metabolism, gets thrown off by unhealthy patterns of sleep or by changes in diet or alcohol consumption. If you're experiencing indigestion or your energy levels are low after too many holiday parties, your liver could be out of sync. In recent years, more and more research in the field of chronobiology, the science of biological rhythms, suggests the importance of maintaining a consistent schedule for the sake of your liver, which has a clock of its own.
Circadian rhythms are important for helping the liver anticipate the body's demands throughout the day, like stockpiling energy after meals and releasing it when we sleep, said Felix Naef, a professor of quantitative biology at the Swiss Federal Institute of Technology in Lausanne.
Recent studies have examined how alcohol affects circadian rhythms. This year, researchers reported that night shift workers given two to four glasses of wine each day for a week had altered circadian rhythms and "leakier" intestinal linings than day workers, which could put them at risk of alcoholic liver disease.
Dr. Garth R. Swanson, a gastroenterologist at Rush University Medical Center in Chicago and an author of the study, says he believes this risk applies to any drinkers who frequently shift their circadian rhythms by more than two hours.
"People don't have to be working night shifts for months or years," he said. "You could potentially put yourself at risk just by doing a series of bad behaviors for a relatively short amount of time."
Other studies in mice have implications for understanding the liver's cycles.
Last month, Dr. Naef and a team of researchers reported finding more than 500 proteins in mice liver cells that shift in abundance over the course of the day. These proteins ultimately help the liver filter blood and process fats and sugars. When they are thrown off their tight schedules, the liver might lag in important processes like detoxification and digestion.
Our daily liver cycles are molded by an interplay between sleep, food and alcohol. Sleep affects the master clock in our brain. Like most other bodily organs, the liver is partly governed by this central rhythm.
But the liver also has its own internal clock, which can be affected by food and alcohol.
In studies with mice, John Y. L. Chiang, a professor of biochemistry at Northeast Ohio Medical University, has found that even short-term changes in either sleep or diet can affect the liver's ability to contribute to fat digestion. Chronic disturbances, he said, may lead to fat accumulation in the liver, which can cause "many different problems: fatty liver disease, diabetes, obesity, heart disease and even cancer."
Alcohol can also knock a mouse's liver rhythms out of whack, said Shannon M. Bailey, a professor of environmental health sciences at the University of Alabama at Birmingham. Her team recently found that feeding mice moderate levels of alcohol for a month significantly disrupted the functioning of their liver clocks.
To keep your liver's clock consistent this holiday season, avoid extreme behaviors, said Lei Yin, an assistant professor of physiology at the University of Michigan.
That means maintaining your central circadian rhythm with a regular sleep schedule. You can stay up a little later, but try to avoid doing so more than two hours past your normal bedtime. A helpful tip is to go on a walk in the mornings. "Light is the most powerful way to reset our internal clock," Dr. Yin said.
It also means staying cognizant of how food and alcohol affect your liver's timers. Try to stick to normal mealtimes. And it's fine to drink a little, but avoid binge drinking, which is defined as more than four or five drinks in two hours.
In the short term, sticking to these guidelines might ease your transition back to reality, once the holidays are over. In the long term, maintaining a regular schedule and drinking less can safeguard your metabolism and prevent disease.
New Year's resolutions, anyone?