Getting less than seven hours’ sleep a night ‘could damage DNA beyond repair’

A lack of sleep could permanently damage DNA and increase the risk of cancer, scientists believe.

Sleep deprivation can also reduce DNA’s ability to repair itself, possibly leading to genetic diseases, findings from a study suggest.

Researchers believe it is the first study of its kind to look into the effects of sleep deprivation on genes in young adults.

The research focused on doctors, known for having to adjust their sleep patterns due to night shift work, and the scientists do not know why a lack of sleep damages DNA.

The recommended amount of sleep is generally seven hours a night, but figures suggest adults routinely miss out on an hour or two. 

A lack of sleep could damage DNA and increase the risk of cancer, scientists at the University of Hong Kong believe on the back of a study (stock image)

The study at The University of Hong Kong looked at 49 working doctors from two local hospitals, 24 of whom had to work overnight on-site calls.

When a doctor receives such a call – on average they get five to six per month – they must work from late afternoon to early morning the next day.

In the study the participants got between two and four hours of sleep during calls, with three getting as little as one hour’s shut-eye.

The remaining 25 doctors were not expected to work these hours.

After three days of a good sleep, researchers took blood samples from all doctors.

Then, blood samples were taken the morning after a night shift when doctors were sleep deprived.

The findings, published in the journal Anaesthesia, showed doctors who worked night shifts had 30 per cent more breaks in their DNA compared to those who did not. 

What’s more, the DNA damage increased a further 25 per cent after a night of sleep deprivation.


Insomnia means you regularly have problems sleeping. It usually gets better by changing your sleeping habits.

You have insomnia if you regularly: find it hard to go to sleep, wake up several times during the night, lie awake at night, wake up early and can’t go back to sleep, still feel tired after waking up

Everyone needs different amounts of sleep. On average, adults need 7 to 9 hours, while children need 9 to 13 hours.

You probably don’t get enough sleep if you’re constantly tired during the day.

The most common causes of insomnia are: stress, anxiety or depression, excessive noise, an uncomfortable bed or alcohol, caffeine or nicotine.

Insomnia usually gets better by changing your sleeping habits. For example, going to bed and waking up at the same time every day, and only going to bed when you feel tired.

Source: NHS

DNA repair was also lower in the doctors who didn’t get adequate sleep, which can cause cell death.

The study authors wrote: ‘DNA damage is a change in the basic structure of DNA that is not repaired when the DNA is replicated. 

‘Double‐strand breaks are particularly hazardous, as repair failure causes genomic instability and cell death, whereas disrepair can lead to inappropriate end‐joining events that commonly underlie oncogenic transformation [cancer formation].

‘Sleep deprivation in shift workers is associated with adverse health consequences. 

‘Increased DNA damage has been linked to the development of chronic disease. 

‘This study demonstrates that disrupted sleep is associated with DNA damage.’

Although the findings are preliminary, Dr Gordon Wong Tin-chun, co-author of the study and an associate professor at HKU’s department of anaesthesiology, said there is an indication the sleep disruption is ‘not good’ for your genes.

He said: ‘[Such conditions] may increase chances of developing diseases from genetic mutations such as cancers.’

It is not clear, according to the researchers, why DNA damage occurs due to a lack of sleep. 

Dr Wong Tin-chun said the findings of the study might be applicable to people who had shift patterns similar to doctors, but that the study is hoped to raise awareness on the importance of getting enough sleep.

The study also highlighted that the doctors were ‘young and healthy’, and therefore more tolerant of a lack of sleep. 

‘Maybe you should consider looking into your [sleep habits] and treating sleep with a bit more respect,’ Dr Wong Tin-chun said.    

The recommended hours of sleep for people vary across age groups. An adult aged between 18 and 60 would need at least seven hours of sleep per night, according to the website of the US Centres for Disease Control and Prevention.

Figures from the Royal Society for Public Health estimate that the average person sleeps for 6.8 hours a night. 

However, it is recommended by the US Centres for Disease Control and Prevention to get at least seven hours per night, and the NHS recommends eight hours.

Regular poor sleep puts you at risk of serious medical conditions, including obesity, heart disease and diabetes.

It shortens your life expectancy, according to the NHS, and has previously been linked to a greater risk of cancer. 

More than 40million people suffer from long-term sleep disorders in the US, data from the CDC shows. While it is estimated there are 1.5million patients in the UK.