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Look out: Lack of sleep can be a probable carcinogen

Look out: Lack of sleep can be a probable carcinogen

Factors like lack of sleep, delayed sleep onset and smoking can lead to cancer. Adequate hydration, deep breathing and exposure to sun can help

Factors like lack of sleep, delayed sleep onset and smoking can be probable carcinogens. However, association of sleep as an independent risk factor for cancer has not been scientifically proven yet

While seven to nine hours of sleep is essential for every individual, it has become difficult for many to go to sleep. Not being able to get proper sleep, difficulty in going back to sleep and a disrupted sleep-wake cycle has led to serious health conditions. Experts say establishing a link between sleep and cancer is not far away.

Scientists from 16 countries who met at the International Agency for Research on Cancer (IARC) found out that working in night shifts can be carcinogenic for humans.

These scientists described that night shift work includes trans-meridian air travel during regular sleeping hours of the general population. Disruption in normal circadian rhythm is the most pronounced effect of night shift work.

Why is sleep important?

“Sleep is the time when the body restores and repairs itself. Just as we recharge our electronic gadgets, we should also allow our body to recharge itself. Instead of blaming stress, we need to look at a broader level to understand where our body is pushed where the strain becomes too much on the nervous system,” said Dr Vishal Rao, group director, head and neck surgical oncology and robotic surgery, HCG Cancer Centre, Bengaluru.

Night shift workers are common in industries which operate around-the-clock (like transport, healthcare, etc.). In such individuals, lack of sleep becomes a co-carcinogen (any substance, organism or agent capable of causing cancer), say experts.

He added, “Post-COVID, there has been an increase in cases of insomnia. This causes improper functioning of the immune system, leading to decreased productivity.”

How does lack of sleep become a carcinogen?

Dr Rao said, “Factors like air pollution, smoking, lack of sleep and a sedentary lifestyle are probable carcinogens, and can be called co-carcinogens because of their collective effect on the body.”

Disturbed sleep leads to low immunity. It affects the immune system, which may cause genetic damage, said Dr Rao.

Studies reveal lack of evidence

The literature on sleep time and cancer risk is mixed. A trio of meta-analyses conducted between 2016 and 2019 found that long sleep duration was associated with a slightly elevated risk of all-cancer mortality in Asians,” said Dr Prasad Narayan, senior consultant and director, medical oncology, Cytecare Cancer Hospitals, Bengaluru.

He says that in the multivariable analysis, longer sleep duration was not associated with total cancer incidence in men. In women, however, sleeping 10 hours or more was associated with a 19 per cent increased risk of cancer compared to sleeping for seven hours.

“Decreased or inadequate sleep can be associated with obesity, lack of exercise, smoking or alcohol addiction, which are all risk factors for cancer. In summary, the association of sleep as an independent risk factor for cancer has not been proven with adequate evidence from scientific studies,” said Dr Narayan.

Ways to get a good night’s sleep

The post-COVID era has taught individuals a lot of ways to stay fit. Dr Rao said that the pandemic has taught us three things that are important for maintaining optimal health, leading to a good night’s sleep:

  • Adequate hydration: Intake of water is crucial. Drinking adequate water and fluids is key to staying properly hydrated.
  • Taking deep breaths: We have stopped taking deep breaths. Practicing deep breathing exercises every day can help to reduce stress.
  • Sun time: We are more exposed to phone screens than to the sun. We need to cultivate the habit of waking up to the sun and not to the phone screen or the alarm. This is disrupting the circadian rhythm. We need to change this habit.


  • Factors like lack of sleep, disturbed sleep, smoking and a sedentary lifestyle can act as co-carcinogens in individuals.
  • The body restores and repairs itself during sleep. A good night’s sleep can help avoid any ill-effects to the circadian rhythm and the immune system.
  • Adequate hydration, deep breathing and exposure to sun can help individuals get a good night’s sleep.

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