If insomnia is as familiar to you as the ceiling you stare up at every night, here’s some bad news: Cancer. Yes, other than the gamut of diseases the lack of sleep has been linked to – including heart disease, high blood pressure, diabetes, obesity and depression – you also have to contend with the Big C.
A 2022 YouGov study on more than 1,000 Singapore residents found that 73 per cent are getting less than seven hours sleep per night and over 30 per cent of them only got five to six hours of shuteye. This is well below the global average and a 44 per cent rise since 2018.
And Singaporeans still aren’t getting enough sleep. According to ResMed’s latest global sleep survey, including over 1,000 Singapore residents, eight in 10 respondents reported one or more symptoms of sleep disruption related to sleep quality. The most common cause of interrupted sleep was obstructive sleep apnoea (81 per cent).
“Sleep is the period when cellular DNA repairs occur and disruptions may lead to the accumulation of genetic mutations, which promotes cancer development,” said Dr Wong. “In addition, poor sleep also leads to impaired immunity as the immune system becomes less able to detect and eliminate cancerous cells.”
There are also those who work the night shift, which is another source of concern as the “exposure to light while working overnight shifts for several years may reduce levels of melatonin, encouraging cancer to grow”, according to Johns Hopkins Medicine.
WHAT ARE THE CANCERS INVOLVED?
Cancers of the breast, colon, ovaries and prostate, according to Johns Hopkins Medicine. Liver and lung cancers may also be added to the cancer and sleep deprivation list. In a 10-year Taiwanese study on over 63,000 patients, it was found that the risks of liver and lung cancers were elevated among those with sleep disorders that aren’t linked to sleep apnoea.
Another study discovered that exposure to light at night may increase the risk of breast cancer.
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“Much of the research on sleep and breast cancer risk is related to shift work and factors related to disrupted sleep patterns, such as the unexpected light exposure at night,” said Professor Charlie Zhong, the principal scientist of epidemiology research at American Cancer Society.
However, he added a caveat: “While it does appear that the light from mobile devices can disrupt sleep, these technologies and how we use them, change so quickly that it has been difficult to study when it comes to longer-term health effects, such as cancer”.
Dr Wong has seen patients who suffered from different cancers such as cancers of the colon, breast, prostate, lung and pancreas in his sleep clinic. “The prevalence would depend on how common some of these cancers are,” he said.
WOULD SLEEPING IN ON WEEKENDS HELP? HOW ELSE CAN YOU REDUCE YOUR RISK?
No such luck. “This is an unknown but in my opinion, it does not help,” said Dr Wong. “Our human body runs on a 24-hour cycle regulated by the circadian rhythm, with specific physiological processes occurring at certain period of the 24-hour day.
“Sleep makes up a significant portion of this and hence, any disruption during the usual sleep period, will interfere with the specific processes occurring during that time.”
But what if you can’t quit your shift work? Are there other ways to lessen your risk of cancer? Besides sleep, diet and exercise are the other pillars of health to look into, said Dr See Hui Ti, a senior consultant, with Parkway Cancer Centre’s Medical Oncology department.
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For instance, eating a healthy and balanced diet can reduce the risk of cancer, noted Cancer Research UK. But the benefit isn’t from any singular cancer-fighting “superfood” that advertisements may have led you to believe. “Your overall diet (what you usually eat in a normal week) is more important than individual foods when it comes to cancer,” noted its website.
As for exercise, physical activity is associated with a lower risk for several types of cancer, including breast, prostate, colon, endometrium and possibly pancreatic cancer, according to American Cancer Society. Physical activity can help regulate some hormones that contribute to the development of cancer and help keep the immune system healthy.