> At 3 a.m., the sounds of keyboards clattering and coffee machines humming in office buildings create a requiem for modern society, and approximately **38% of adults** worldwide are paying the price for it in terms of health.
About 38% of adults worldwide are experiencing chronic sleep deprivation; their bodies are like biological instruments on fast-forward, conducting dangerous metabolic experiments in the dark.
According to a World Health Organization survey, **27% of people worldwide have sleep problems**. Sleep disorders have become the second most common mental disorder globally, affecting one in three people and meeting the formal diagnostic criteria for insomnia.
Even more worrying is a joint report released by the World Health Organization and the International Labour Organization, which indicates that nearly 2 million people die each year globally from occupational diseases and injuries, many of which are caused by long working hours and excessive use of electronic devices.
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## 01 Sleep Problems, a Global Health Hazard
Insufficient sleep has become a global health problem that cannot be ignored. Statistics show that approximately 450 million people worldwide work more than 55 hours per week, and 745,000 people die annually from strokes and heart attacks caused by long working hours.
The number of people suffering from sleep problems is even larger, with 27% of the global population experiencing sleep issues. Sleep disorders are the second most prevalent mental health disorder globally, second only to mood disorders.
The health risks of staying up late should not be underestimated. Studies show that frequently staying up late can lead to weakened immunity, dull complexion, decreased vision, gastrointestinal disorders, forgetfulness, insomnia, and other symptoms of sleep deprivation syndrome, threatening our physical and mental health.
## 02 Brain Cleansing, Nighttime Paralysis
Sleep is the golden time for the brain to cleanse and repair itself. Scientific research shows that during sleep, cerebrospinal fluid flow increases by 60%. This clear fluid flushes the synaptic cleft at a rate of 20 ml per minute, transporting metabolic waste such as β-amyloid protein into the lymphatic system.
The brains of those who stay up late are like clogged drains, with **Alzheimer’s disease-related proteins depositing 27% faster than normal**, equivalent to prematurely aging the cerebral cortex by 0.4% per year.
Functional MRI showed that after three consecutive days of less than 6 hours of sleep, the glucose metabolism rate in the prefrontal cortex decreased by 12%, and the rate of decision-making errors increased by 40%.
A study in Science Translational Medicine further confirmed that sleep deprivation reduces the ability of microglia to remove β-amyloid protein from the brain, and β-amyloid protein is one of the important markers of Alzheimer’s disease.
## 03 Gene Expression, in Disorder
Of the 23,000 genes in the human body, **711 exhibit circadian rhythmic expression**. Staying up late leads to abnormal methylation of the CLOCK gene, increasing the expression level of the fat synthesis-related gene FASN by 3 times and accelerating the rate of triglyceride deposition in the liver by 50%.
Even more alarming is the damage to reproductive cells: **After three consecutive weeks of staying up all night, men’s sperm DNA fragmentation index soared from 15% to 32%**, equivalent to the level of reproductive cell aging in a 45-year-old man.
The effects of staying up all night differ between men and women. A research team from the University of Pennsylvania found that men are more susceptible to disruptions to their “biological clock” caused by staying up all night or shift work, and their incidence of metabolic syndrome due to circadian rhythm disorders is significantly higher than that of women.
## 04 The Immune System, Completely Turned Against It
Deep sleep is a crucial period for the repair and strengthening of our immune system. During deep sleep, the activation of integrin α4β7 on the surface of T cells **increases by 200%**, and these immune sentinels patrol the lymphatic vessels in an orderly manner.
When sleep time is reduced to 5 hours, **NK cell activity decreases by 70%**, and the reactivation rate of latent EB virus increases to four times the normal value.
Actual hospital statistics show that the incidence of shingles among nurses working long night shifts is 3.2 times that of the day shift group, and the antibody response rate to the flu vaccine is reduced by 56%.
## 05 Metabolic Factory, Chain Reaction
Staying up late disrupts our metabolic system. Orexin neurons in the paraventricular nucleus of the hypothalamus continue firing while awake, causing **ghrelin secretion to be 55% higher than during sleep**.
PET-CT scans show that when night owls are faced with high-calorie foods, **dopamine release in the nucleus accumbens increases by 37%**, while prefrontal cortex inhibitory signals decrease by 63%. This imbalance in the neural reward mechanism leads to an 11% annual increase in visceral fat in nighttime eaters, 2.3 times that of the non-night-owl group.
A study from the University of Groningen Medical School in the Netherlands tracked the sleep habits and health of nearly 24,000 people for 10 years and found that habitual night owls experienced a **faster decline in cognitive ability** than early sleepers.
## 06 Cardiac Burden, Nearing its Limit
Huo Xiaochuan, Deputy Chief Physician of the Department of Cerebrovascular Diseases at Beijing Anzhen Hospital, Capital Medical University, stated that staying up late itself may not directly cause sudden death, but it **significantly increases the risk of sudden death**.
You must rest immediately if any of the following four situations occur: **sleep less than 4 hours a day for more than 3 consecutive days**; do not catch up on sleep after staying up all night; consistently sleep less than 6 hours a day; or combine staying up late with high-pressure work or exercise during the day.
Studies show that sleeping less than 4 hours a day for several consecutive days is equivalent to keeping your heart beating at a high speed for 72 hours straight. During normal sleep, heart muscle cells can undergo 40% repair, but this repair almost stops when sleep is deprived.
In this state, **myocardial oxygen consumption increases 3 times**, and the probability of vasospasm increases to 5 times the normal level.
## 07 Repairing Damage: Expert Advice
Patrick Fuller, a sleep scientist and assistant professor of neurology at Harvard Medical School, shares some secrets to a good night’s sleep:
– **Wake up at the same time every morning**, no matter how late you go to bed.
– **Avoid consuming stimulants in the afternoon**, as caffeine has a long half-life and takes more than 6 hours to be eliminated from the body.
– **Maintain at least 20 to 30 minutes of exercise daily**, exercising in the morning or afternoon can improve sleep quality at night.
– **Avoid drinking alcohol at night**, according to the National Institutes of Health, drinking alcohol before bed reduces REM sleep time.
– **Create a sleep-inducing environment**, dim the lights an hour before bed each night.
– **Avoid screen time an hour before bed**, as smartphone and tablet screens reduce melatonin, hindering sleep.
Remedies after staying up late are also important. Doctors recommend several methods: **catch up on sleep promptly**, even if you have difficulty falling asleep, it’s advisable to rest in bed; **eat a light diet**, focusing on low-calorie foods rich in B vitamins and protein; and **exercise moderately**, such as gentle exercises like Baduanjin or Tai Chi.
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A study of human and animal sleep over the past 20 years shows that **insufficient sleep can potentially cause lasting brain damage**. Researchers found that persistent sleep deprivation is particularly damaging to the brain.
Dr. Sigrid C. Veasey, a neuroscientist at the University of Pennsylvania, points out: “How much sleep deprivation leads to brain damage? Based on all previously published research, **a week of chronic sleep deprivation can cause some degree of brain damage**.”
When we stare at the glowing screens of the night, perhaps we should also listen to the mournful calls of our ancient biological clocks deep within our bodies.