Feeling uncomfortable all over after staying up late is actually a confusing warning from your organs

"Just a little more checking of my phone, one more episode of the show, and then I'm off to bed."

"After I finish this report, I'll go to bed."

Such self-commitment seems to have become a fixed ritual in our nights. After nightfall, the flashing screen of mobile phones or computers has become an indispensable companion for many people. Such scenes seem to have become a regular script for many people's nights.

In the fast pace of modern life, staying up late has almost become a norm. Whether it is the pressure of work, the burden of schoolwork, or the endless temptation of social media and entertainment programs, there seem to be endless reasons for us to postpone going to bed. The quiet moments of the night are filled with these complicated activities, leaving us on the edge of going to bed late.

However, the consequences of staying up late for a long time are not just temporary fatigue or drowsiness the next day. Its impact is far more profound than we think. From the heart to the kidneys, from the liver to the brain, these core organs of the body are quietly bearing the burden of staying up late. Staying up late not only changes our biological clock, but also sends a warning signal to our physical health that cannot be ignored. Our body is sending us a strong signal that we need to rest and recover.

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Heart: Rest at night and burden during the day

Night is a precious time for the heart to relax. At this time, its nervous system should smoothly transition from the busy sympathetic state during the day to the control of the vagus nerve at night. This transition allows the heart to rest and the heart rate naturally slows down. However, when staying up late, the sympathetic nerves are constantly in an excited state, which not only makes it difficult for our hearts to get the rest they deserve, but may also cause blood pressure to continue to rise. This impact is not a trivial matter. Studies have shown that people who sleep less than 6 hours a night are 20% to 32% more likely to develop high blood pressure, and the impact on women is particularly significant.

Staying up late not only causes blood pressure problems, but also reduces sleep time and is closely related to an increased risk of coronary heart disease. When lack of sleep becomes the norm, our heart will face a 48% increase in the risk of coronary heart disease. The heart, the energy source of the body and the core of blood circulation, once a problem occurs, it may affect the health of organs throughout the body and even become the cause of sudden death. Studies have found that people who have difficulty sleeping have an increased risk of cardiovascular death by about 45%.

Kidneys: A delicate balance of circadian rhythms

The kidneys will also inevitably be harmed by staying up late. Studies have found that the kidneys also have a circadian rhythm. As night falls, the working mode of the kidneys will also change, such as the reduction of urination at night and the change of urine pH. The urine is alkaline during the day and acidic at night.

However, this delicate system is disrupted by the habit of staying up late. When we postpone sleep and ignore the body's natural rhythm, the kidney's circadian rhythm is also disrupted. This is not just a simple time adjustment problem, but a potential damage to kidney function. Studies have found that shortened sleep time is closely related to decreased kidney function. On average, for every hour of sleep reduction, the glomerular filtration rate decreases by 1.1ml/min/1.73m^2. Although this change is small, the impact on kidney health is long-term and profound.

Image from reference [4]

To be more specific, people who sleep less than 6 hours a night are more than twice as likely to report chronic kidney disease as those who sleep 7 to 8 hours a night. This data reveals a fact that cannot be ignored: our nighttime habits may be quietly eroding our kidney health.

The liver: the metabolic factory and its relationship to sleep

At night, when the world falls asleep, the liver quietly carries out its night shift. This sleepless chemical factory processes various metabolites at night to maintain the balance in our body. However, the habit of staying up late interferes with this delicate biological process. Lack of sleep not only affects our mental state, but also poses a potential threat to our liver health.

Lack of sleep can induce our appetite by increasing the level of appetite-inducing hormone-ghrelin and reducing the level of leptin, which controls satiety, which usually leads to weight gain; at the same time, lack of sleep can also lead to impaired insulin sensitivity. These are risk factors that endanger liver health. Specifically, the risk of non-alcoholic fatty liver disease in people with reduced sleep time increases by 15%.

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Brain: The importance of a night's rest for clear thinking

In our daily lives, the brain is undoubtedly the most diligent worker. It processes daily thoughts, emotions and memories, and even weaves dreams and organizes memories when we are asleep. However, when it is late at night and we are still immersed in staying up late, our brain is deprived of the rest and recovery time it deserves.

The effects of staying up late on the brain are immediate. The next day, we often feel slow in thinking and unable to concentrate. But this is just the tip of the iceberg. The damage to the brain caused by long-term lack of sleep is profound and hidden. Memory, concentration and vigilance will all be impaired by long-term staying up late.

Even more profound is that compared with people who get a full 6 to 8 hours of sleep per night, those who sleep less than 6 hours have smaller brain volumes, such as a 2.0% decrease in the volume of the right nucleus accumbens to a 0.5% decrease in the volume of the right anterior pole.

Image from reference [9]: People who sleep 6 to 8 hours have larger brain volumes

The impact of staying up late goes far beyond temporary fatigue. It profoundly affects the health of our heart, kidneys, liver and brain. These long wake-up hours at night are not just the passage of time, but also the continuous consumption of body functions.

Therefore, maintaining good sleep habits is not just a simple adjustment to life, it is an important maintenance of overall health. Let us value every quiet night and ensure adequate sleep time, which is the most basic and most important care for our own health.

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This article is a work of Science Popularization China-Starry Sky Project

Produced by: Science Popularization Department of China Association for Science and Technology

Producer｜China Science and Technology Press Co., Ltd., Beijing Zhongke Xinghe Culture Media Co., Ltd.

Author: Jiang Yongyuan, Master of Internal Medicine, Third Military Medical University

Reviewer: Tang Qin, Director and Researcher of the Science Popularization Department of the Chinese Medical Association