Can’t Sleep in Summer? Staying Up Late Is Quietly Destroying Your Health — Doctor Luo Dalun on Sleep: Late Nights First Hurt the Liver and Yin Blood, and Finally the Kidney Essence

Patient search terms: can’t sleep in summer / staying up late / sleep deprivation / not sleeping at night / heat above cold below / mouth ulcers / prematurely gray hair

Corresponding medical names: sleep deprivation · insomnia · liver-kidney yin deficiency · kidney essence deficiency · deficient fire flaring upward

Opening: on a hot summer night, the streets are full of people

Summer has arrived, and in many places the heat makes it genuinely hard to fall asleep at night. Yet this is precisely the season of “carnival” — why? Precisely because sleep is so hard to come by, people simply decide not to sleep at all.

💬 Note from Doctor Luo: In the northeast, basically everyone heads out to the street for barbecue — friends gather, pull up little stools, and drink beer with grilled skewers. In the south it’s hot too, but once night falls and it cools off, people come out — to do what? Late-night snacks. So in many places summer is a season of celebration, and basically everyone stays up late. Someone who usually goes to bed at 11 p.m. might routinely go to bed at 1 or 2 a.m. Summer nights become a real problem — many people’s sleep gets cut dramatically short. So what exactly does this reduced sleep damage in our bodies? What consequences does it bring? Today let’s talk about this.

For tens of thousands of years, humans have lived “with the sun”

To understand why sleep matters, we first have to look back at human history. The lifestyle of modern people has changed dramatically compared with the ancients.

💬 Note from Doctor Luo: Human evolution spans at most tens of thousands of years, and through almost all of it, humans slept at night. Back when we were cave-dwelling hominids living off raw meat and blood, night hunting was basically impossible — and going out at night was dangerous. You couldn’t see what was out there, but there were nocturnal predators, so people rested in the treetops and slept once it got dark. In the farming era, candles and oil lamps existed, but they cost money — to save money, ordinary people also went to sleep at night. Maybe scholars lit lamps to read, but ordinary folk lived by the sun: rise at sunrise, sleep at sunset, and once the sun went down, everyone slept. So throughout humanity’s long history, life followed the sun: the sun comes up and we begin our activities; the sun goes down and we sleep.

Electric lights, smartphones, TV series: sleep gets “stolen”

But the modern way of life has completely overturned this rhythm.

💬 Note from Doctor Luo: Because we have electric lights and easy ways to go out, modern people suddenly stopped sleeping at night. And more recently we got smartphones — phones with WeChat, all kinds of entertainment, and the ability to watch TV. Many people lie in bed watching TV series on their iPads — for example My First Half of My Life (Wo De Qian Ban Sheng) — reportedly watching until the middle of the night, episode after episode. This causes a dramatic reduction in sleep. So what does reduced sleep actually injure? What changes does it cause in the body? This is a bigger problem than people realize.

What is the body doing at night? — Yin blood returns to the liver, and the twelve meridians take turns “on duty”

Night is the body’s rest time, and in fact every part of the body is resting.

💬 Note from Doctor Luo: Chinese medicine holds that at night yin blood returns to the liver and the liver meridian is nourished, which also prepares for the rising of yang qi the next morning — so night is when the blood rests. Chinese medicine also has a theory: over the course of a day, qi and blood reside in different meridians, and the twelve meridians flow in a set sequence — from 3 to 5 a.m. the lung meridian begins, then in order: lung, large intestine, stomach, spleen, heart, small intestine, bladder, kidney, pericardium, triple burner, gallbladder, liver. You see, finally, from 11 p.m. to 1 a.m. it’s the gallbladder meridian’s shift, and from 1 to 3 a.m. the liver meridian’s shift. People believe this is when the body detoxifies, flushing out the waste products inside.

Science confirms: the brain really does “detox” at night

In the past we assumed these were just Chinese medicine’s inferences. Now look — it really is true.

💬 Note from Doctor Luo: Take the brain, for example — why do people sleep? Scientists used to be unable to figure it out. Recently they discovered: at night, the brain cells shrink. Shrink for what? To leave gaps between the cells. At this point the cells push the waste products of the day’s activity into these gaps, and then cerebrospinal fluid begins to flow, flushing the waste away — you see, that’s detoxification. So some people who don’t get enough sleep haven’t had their brain waste cleared out, and the next day they’re foggy and just want to sleep — why? Because the body wants to clean it for you; once it’s cleaned, the brain cells can function normally again. See, it really is detoxification. This conclusion was proven by a paper published not long ago, confirming that the ancients’ experience was right.

First it injures the liver and yin blood; in the end it injures the kidney essence

Night is the body’s opportunity to repair and detoxify — to flush out the waste produced by the day’s activity. If you keep shrinking that opportunity, the body can’t repair itself, and damage accumulates. So what exactly gets damaged?

💬 Note from Doctor Luo: First, the liver and yin blood are injured, and eventually the kidney essence (shen jing) is damaged. Kidney essence is a special concept in Chinese medicine: the essence inherited from your parents is called prenatal essence (xian tian zhi jing). Combined with the essence of the food we take in after birth — the most refined nutrients — plus the clear fresh qi we breathe in, these postnatal nutrients form the postnatal essence (hou tian zhi jing), which is sealed and stored in the kidneys. The concept of kidney essence is extremely important: essence generates yin and yang — essence is like primordial chaos, a chaotic substance containing both yin and yang, and from it yin and yang emerge. In the past we always classified essence under yin, but actually essence is a more fundamental thing. Laozi’s Tao Te Ching says, “The Dao gives birth to one; one gives birth to two; two gives birth to three; three gives birth to all things” — that “one” is essence, and only from it do yin and yang emerge. Kidney yin and kidney yang are both born from essence. So if we excessively consume yin, or excessively consume yang, what gets damaged in the end is this kidney essence — the fundamental substance of your life gets consumed. That makes a person age quickly, skin problems appear, digestive problems appear, and the body’s whole process of growth and renewal has trouble.

What does kidney essence deficiency look like? — fire blazing above, ice below

What does kidney essence deficiency feel like? Doctor Luo has explained this many times.

💬 Note from Doctor Luo: People with kidney essence deficiency often develop a state of yin and yang separating (yin yang jue li) — deficient fire flares upward, so the upper body is hot and the lower body is cold. Up top, they constantly have mouth ulcers, or toothache, or sore throat, or headaches and dizziness, or red swollen eyes — in short, fire keeps flaring up above. Down below, the knees, ankles and legs are cold and fear wind and chill. The upper body gets hotter and hotter, the lower body colder and colder; yin and yang cannot meet, water and fire cannot harmonize (shui huo ji ji) — and so these people develop all these problems.

“I have no sex life — how can my kidney essence be deficient?” — staying up late hurts just the same

Doctor Luo has recently met many people with kidney essence deficiency and all kinds of related complaints.

💬 Note from Doctor Luo: I look at them and say, your kidney essence is deficient — for example, some people’s spleen and stomach are failing, digestive problems everywhere. They say: how can my kidney essence be deficient? I haven’t had sex with my wife for a long time. There’s no such thing happening. I say that’s not necessarily what caused it — if you stay up late night after night, that also depletes kidney essence. Think back on your own habits. He says: of course I do — I go to bed at 1 or 2 a.m. every night, it’s a lifelong habit. Everyone, what is this? This is consuming kidney essence! And I still have to go to work during the day. So remember: kidney essence deficiency is a common feature of modern people — prematurely gray hair, teeth falling out early, heat above and cold below, the body always out of balance. And of all these cases of kidney essence deficiency, a huge proportion is caused by not sleeping — because modern people’s sleep patterns are completely different from the ancients’, and the state of not sleeping has become an extremely common phenomenon.

Today’s children: 80-90% are not sleeping properly

What worries Doctor Luo most is the younger generation.

💬 Note from Doctor Luo: Parents today tend to be permissive with their children — relaxed, hands-off, giving them as much freedom as possible. Of the children I see in my clinic, basically 80-90% are not sleeping properly — up chatting on the internet at night, or binge-watching TV series into the small hours. Once they’re at university you can’t control them; they watch shows every night and you never know. These health concepts need to be taught to children. Children with kidney essence deficiency are listless all day, pale-faced, can’t even stand up straight — their bodies twist and fidget — why? Insufficient upright qi (zheng qi). Such young people will have health problems later in life. From this perspective, sleep’s protection of our health is extremely important.

Give your body a chance to repair: sleep at 9 p.m., wake at 7 a.m.

Many people come with all kinds of illnesses and problems, and Doctor Luo gives them all the same advice.

💬 Note from Doctor Luo: I say, if you can persist for one week — go to bed at 9 p.m. every night and sleep until 7 a.m. — even if you can only manage falling asleep at 7 and waking at 7, persist for a week and your body will noticeably improve. Why? Because you have to give your body a chance to repair. You stay up late watching shows at night, then go begging for medical help during the day — “why is my body so bad?” Because you never gave your body a chance to repair itself. So everyone, if you check your social feed in the morning and see someone posting on WeChat at 2 a.m., you sigh: this person doesn’t cherish their body. Going out for barbecue every night, living it up — that’s also not cherishing your body. Trading temporary pleasure for damage to your health is not a good deal.

Learning Chinese medicine starts with “following nature”

Finally, Doctor Luo brings the topic back to the fundamentals of learning Chinese medicine.

💬 Note from Doctor Luo: I think modern people should reflect: is our sleep consistent with the ancients’? Is the state of sleep deprivation reasonable? Is it worth damaging our health — going without sleep — just to go out and play? Learning Chinese medicine means first learning to understand yourself and the patterns of change in the natural world. Once you understand them, you know how to live. They’re all small things, really — put these small things back in their proper place, restore them to a normal state, and your body will gradually readjust. If your state of being is always at odds with nature’s changes, and you still hope to stay healthy — I think that hope is slim. Everyone, in the heat of summer, let’s sleep well — what’s affected is the liver, kidneys and yin blood, and ultimately the kidney essence, the most fundamental substance of our lives. To damage it for the sake of not sleeping is not worth it. That’s all for today — I’ll talk more about Chinese medicine topics with you when the opportunity comes.

(Compiled from Doctor Luo Dalun’s sleep and health lecture.)