Insufficient Sleep Increases Cancer Risk

Sleep is essential for rest and regulation throughout the body, especially brain function. Yet the demands of modern life mean many people do not get enough. This can harm general health and contribute to various problems. Recent research suggests that insufficient sleep may increase cancer risk, making a review of sleep habits and a healthy routine a potentially important step towards reducing that risk.

A Study of Insufficient Sleep and Cancer Risk

A study found higher cancer risk among people sleeping less than 6 hours at night, those who did not nap during the day and those sleeping less than 7 hours in total.

Researchers analysed 14,851 participants over age 45 in the China Health and Retirement Longitudinal Study. They assessed relationships between cancer and night-time sleep, daytime napping and total sleep duration.

Study Findings

Participants had an average age of 58.8, and 53% were women.

29% slept less than 6 hours at night, and 46.9% did not nap during the day.

During an average follow-up of 6.9 years, 229 new cancer cases were identified.

In multivariable analysis, people sleeping less than 6 hours at night had a 41% higher cancer risk than those sleeping 6-8 hours. When the researchers analysed participants by sex, the association was significant only among women.

People who did not nap had a 60% higher cancer risk than those napping for more than 1 hour during the day. The association between napping and cancer risk did not differ by sex.

People sleeping less than 7 hours in total had a 69% higher cancer risk than those sleeping 7-8 hours. When participants were analysed by sex and body mass index (BMI), risk was significantly higher in men sleeping less than 7 hours in total and in people with BMI of 24 kg/m2 or more. The differences were not statistically significant in women or people with BMI below 24 kg/m2.

Commentary

This study provides new evidence on sleep duration and cancer incidence from both static and dynamic perspectives.

The researchers proposed several possible mechanisms linking insufficient sleep with cancer risk, including

• reduced melatonin levels,
• impaired immune function and
• disruption of circadian, or biological, rhythms, which could promote tumour development.

The study helps us understand how sleep duration may affect cancer risk and highlights the importance of sleep habits for health. Establishing a healthy routine and monitoring sleep duration may therefore be important steps towards reducing cancer risk.

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Siestas and Midday Naps in China

Daytime napping is widespread throughout China and across Asia. In China, a midday nap is viewed as a healthy complement to night-time sleep, and around 88% of the population take one.

Napping at work is common in China. Lunch breaks are often long, frequently lasting 2 hours, and many people use the time to sleep. Employees commonly take a short nap around midday.

The cultural rationale is to restore the body’s balance of yin and yang. Napping is especially encouraged among students, helping them feel more energetic in the afternoon.

Daytime napping is also common among older adults in China, and studies have examined its relationship with cognitive performance.

Overall, China’s daytime napping culture plays an important role in maintaining health and energy and is embraced by a broad section of society.