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How Staying Up Late Affects Your Body

When you stay up late, you’re hurting your brain, heart, intestines, kidneys and liver. This article explores all the ways night owls might be affecting their health.

A woman looking dazed while staring at a laptop; a clock showing 5 minutes to midnight on her desk.

Why do some people stay up late? In 2021, Universiti Kebangsaan Malaysia and University of Malaya conducted a survey on more than 11.000 working adults in Malaysia to find out why people weren’t getting enough sleep. The results were eye-opening.

More than half of the respondents admitted that they spread themselves too thin. A total of 6,212 respondents only got 6.49 hours of sleep per night on average. The reasons varied from old age, being former or current smokers, high psychological distress to having children, lifestyle factors (work stress, health issues, financial problems), poor sleeping conditions and other mental health concerns. 

Overall, our modern-day obligations or predicaments keep us awake and cause us to delay our night time slumber. It might not be easy to change our daily habits but taking a break from life’s responsibilities to catch some z’s at a reasonable hour is crucial for us to stay alive and well. Read more as we explain what staying up late could do to your body and why it might be dangerous for your health.

Why We Shouldn’t Stay Up Late 

The National Sleep Foundation suggests that the ideal sleeping duration for adults should last seven to nine hours. A 2021 study by European Health Journal concludes that you should go to bed sometime from 10 to 11pm to keep your heart healthy. Similarly, Traditional Chinese Medicine (TCM) also thinks it’s best that adults sleep by 11pm.

If we miss the recommended bedtime at 10 to 11pm, our normal reaction would be to replace our sleep. We assume that if we hit the sheets at 5am and wake up at noon, we’re getting adequate rest because we slept for seven hours. However, this assumption is wrong. Since we didn’t fall asleep within the ideal sleep window, there is a reduction in our sleep quality and you’ll still feel tired when you wake up.

Lacking sleep can harm our organ systems, leading to several severe medical conditions including: 

A woman yawning while lying back on her seat inside a car.
You may feel tired during the day if you stay up late the night before.

Side Effects on the Body’s Organs When You Stay Up Late 

These organs will bear the brunt of your all-nighters: 


Researchers have found a direct link between staying up late and the prevalence of cardiovascular diseases (CVD) in adults.

Since blood pressure drops during sleep, people who don’t get enough night time rest would be more likely to suffer from hypertension, a risk factor for heart disorders like stroke. Evidence has also found a correlation between later bedtime and other causes of CVD: Diabetes and obesity. It not only worsens the glycaemic control in type 2 diabetes patients but staying up late also leads to a higher BMI and, therefore, obesity. 

Low-quality sleep has also been found to trigger inflammation and stimulate atherosclerosis. A condition where plaque builds up in the arteries and limits the blood flow to the heart and other organs, atherosclerosis can result in death.


In a 2017 study conducted by the University of Geneva, scientists in Switzerland discovered that the liver adapts to your sleep-and-wake cycle and functions according to it. Our liver learns your body’s circadian rhythm by taking notes of its active (daytime) and passive (night) phases. Because of this, your liver expands during the day and shrinks to its original size at night. Staying up late would confuse and disturb the workings of the liver. Another study published in 2020 has also found that insufficient nocturnal sleep can increase the risk of liver fibrosis. 

Likewise, TCM believes that sleeping late can disrupt the Liver’s performance. Blood circulation focuses on our liver between 11pm and 3am. If we’re still awake during that time, your Liver will have to work harder and may impair itself. Since it plays a huge role in eliminating toxins, a damaged Liver will severely affect your health. 


Evidence shows that our sleep-wake cycle is influenced by the release of cytokines. These are small proteins that regulate the growth and activity of other cells. Consequently, sleep loss can activate inflammatory cytokines found in most gastrointestinal disorders like gastroesophageal reflux disease (GERD), irritable bowel syndrome (IBS), and colorectal cancer. In addition, shorter sleep duration is associated with obesity, a risk factor for GERD and colorectal cancer. 

What’s more, people who stay up late usually eat during the recommended sleeping hours. This unhealthy behaviour can further harm your stomach. 

A female employee eating instant cup noodles at her work desk, surrounded by stacks of papers.
Unhealthy dietary habits are common in people who stay up late


As you sleep, your blood pressure dips. However, this natural process doesn’t happen with all-nighters. In turn, your sympathetic nervous system is activated at night, causing stress. 

Sleep also helps clear out toxic substances like beta-amyloid protein. It is found in dementia patients and deteriorates their cognitive function. It can be deduced that sleep disruption can impact your cognitive performance and ability to react, pay attention and memorise, among others. 


Poor sleep quality can manifest into several skin-related issues, particularly around the eyes and mouth. This may be due to fatigue that causes droopy eyelids and mouth corners.

A 2015 study conducted in the United States has found a link between chronic poor sleep quality and skin ageing. People who sleep for seven to nine hours daily have better skin barrier functions and are satisfied with their physical attractiveness, in comparison to people who sleep for less than five hours a day.


A 2017 study conducted by researchers for the Kangbuk Samsung Health Study in South Korea has found that people with poor sleep quality have increased glomerular hyperfiltration. This condition is associated with the early phases of kidney diseases.

Another study by the Journal of the American Society of Nephrology also reached a similar conclusion. The finding revealed that sleep disturbance could trigger proteinuria (excessive protein in the urine), causing kidney diseases. 

Sleeping on time, getting quality sleep and not staying up late is necessary to maintain your health. So, if you’re a night owl, you need to take care of your organs. Or better yet, reorganise your daily schedule so you can be in bed by 11pm! 

This is an adaptation of an article, “Can You Regain Your Sleep After Staying Up Late?”, which first appeared on Eu Yan Sang website


  1. Dove Press. 2021. Prevalence of Insufficient Sleep and Its Associated Factors Among Working Adults in Malaysia [Accessed 28 March 2022] 
  2. Sleep Health. 2015. National Sleep Foundation’s sleep time duration recommendations: methodology and results summary [Accessed 28 March 2022] 
  3. Oxford Academic. 2021. Accelerometer-derived sleep onset timing and cardiovascular disease incidence: a UK Biobank cohort study [Accessed 28 March 2022] 
  4. National Institutes of Health. 2019. How disrupted sleep may lead to heart disease [Accessed 29 March 2022] 
  5. Science Daily. 2017. The liver increases by half during the day 
  6. SAGE Journals. 2020. Insufficient nocturnal sleep was associated with a higher risk of fibrosis in patients with diabetes with metabolic associated fatty liver disease [Accessed 29 March 2022] 
  7. National Center for Biotechnology Information. 2015. Sleep Dysfunction and Gastrointestinal Diseases  [Accessed 29 March 2022] 
  8. Pubmed. 2011. Poor sleep quality, stress status, and sympathetic nervous system activation in nondipping hypertension [Accessed 29 March 2022] 
  9. Pubmed. 2018. β-Amyloid accumulation in the human brain after one night of sleep deprivation  [Accessed 29 March 2022] 
  10. National Center for Biotechnology Information. 2017. Sleep duration and quality in relation to chronic kidney disease and glomerular hyperfiltration in healthy men and women  [Accessed 29 March 2022] 
  11. Pubmed. 2019. Renal hyperfiltration defined by high estimated glomerular filtration rate: A risk factor for cardiovascular disease and mortality [Accessed 29 March 2022]
  12. National Library of Medicine. 2015. Does poor sleep quality affect skin ageing? [Accessed 30 May 2022]
  13. American Academy of Sleep Medicine. 2013. Study reveals the face of sleep deprivation. [Accessed 30 May 2022]

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Reviews (2)

Trina mcvayMay 13 2023

Very informative. I stay up all the time and I hate it

MyraMay 03 2023

Very informative!Thanks!

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